U.S. Senators Ben Cardin (D-MD) and Lisa Murkowski (R-AK) speak at a news conference after competing measures to end the partial U.S. government shutdown fell short in the Senate on Capitol Hill in Washington, U.S., January 24, 2019. REUTERS/Leah Millis 

U.S. Senator Ben Cardin (D-MD) addresses the partial federal shutdown with residents of the Pickersgill Retirement Community in Towson, Maryland, U.S. January 7, 2019. REUTERS/Jonathan Ernst 

U.S. Senator Ben Cardin (D-MD) addresses the partial federal shutdown with residents of the Pickersgill Retirement Community in Towson, Maryland, U.S. January 7, 2019. REUTERS/Jonathan Ernst 

U.S. Senator Ben Cardin (D-MD) addresses the partial federal shutdown with residents of the Pickersgill Retirement Community in Towson, Maryland, U.S. January 7, 2019. REUTERS/Jonathan Ernst 

Sen. Ben Cardin (D-MD) speaks at a demonstration against U.S. President Donald Trump's immigration policy outside the U.S. Capitol in Washington, U.S., June 21, 2018. REUTERS/Aaron P. Bernstein 

Sen. Ben Cardin (D-MD) speaks at a demonstration against U.S. President Donald Trump's immigration policy outside the U.S. Capitol in Washington, U.S., June 21, 2018. REUTERS/Aaron P. Bernstein 

Sen. Ben Cardin (D-MD) speaks at a demonstration against U.S. President Donald Trump's immigration policy outside the U.S. Capitol in Washington, U.S., June 21, 2018. REUTERS/Aaron P. Bernstein 

Singer Charlotte Cardin arrives on the red carpet for the 2018 Juno Awards in Vancouver, British Columbia, Canada, March 25, 2018. REUTERS/Ben Nelms 

Senator Ben Cardin (D-MD) speaks as Senate Minority Leader Chuck Schumer (D-NY) listens during a press briefing on Capitol Hill in Washington, U.S., January 30, 2018. REUTERS/Joshua Roberts 

Sen. Ben Cardin (D-MD) speaks with reporters ahead of the party luncheons on Capitol Hill in Washington, U.S. January 23, 2018. REUTERS/Aaron P. Bernstein 

Senator Ben Cardin (D-MD) arrives at Democratic Party caucus meeting on Capitol Hill in Washington, U.S., January 19, 2018. REUTERS/Yuri Gripas 

Senator Bob Corker (R-TN) speaks with Senator Ben Cardin (D-MD) as they arrive for a nomination vote at the U.S. Capitol in Washington, U.S., December 19, 2017. REUTERS/Joshua Roberts 

U.S. Senators (L-R) John Cornyn (R-TX), Richard Durbin (D-IL) and Ben Cardin (D-MD) meet with Jordan's King Abdullah (2nd L) on Capitol Hill in Washington, U.S., November 28, 2017. REUTERS/Yuri Gripas 

Jordan's King Abdullah shakes hands with Senator Richard Durbin (D-IL) as senators John Cornyn (R-TX) and Ben Cardin (D-MD) (R) look on before their meeting on Capitol Hill in Washington, U.S., November 28, 2017. REUTERS/Yuri Gripas 

U.S. Senators (L-R) John Cornyn (R-TX), Richard Durbin (D-IL) and Ben Cardin (D-MD) meet with Jordan's King Abdullah (2nd L) on Capitol Hill in Washington, U.S., November 28, 2017. REUTERS/Yuri Gripas 

Sen. Ben Cardin (D-MD) speaks at a news conference about the latest republican effort to repeal and replace the Affordable Care Act on Capitol Hill in Washington, U.S. September 25, 2017. REUTERS/Aaron P. Bernstein 

Sen. Ben Cardin (D-MD) speaks at a news conference about the latest republican effort to repeal and replace the Affordable Care Act on Capitol Hill in Washington, U.S. September 25, 2017. REUTERS/Aaron P. Bernstein 

U.S. President Donald Trump's nominee for ambassador to Italy Lewis Eisenberg (2nd L), nominee for ambassador to Britain Robert Wood "Woody" Johnson (C) and nominee for ambassador to Canada Kelly Knight Craft (2nd R) arrive with committee chairman Senator Bob Corker (R-TN) and ranking member Senator Ben Cardin for the Senate Foreign Relations Committee hearing on their nominations on Capitol Hill in Washington, U.S. July 20, 2017. REUTERS/Jonathan Ernst 

U.S. Senator Susan Collins (R-ME) (C), trailed by Senator Angus King (I-ME) (2nd R) and Senator Ben Cardin (D-MD) (R), walks to the Senate floor at the U.S. Capitol in Washington, U.S. July 18, 2017. REUTERS/Jonathan Ernst 

William Francis Hagerty IV (2nd R) poses with Senators Lamar Alexander (R-TN) (L), Bob Corker (R-TN) and Ben Cardin (D-MD) (R) before the Senate Foreign Relation committee nomination hearing to be ambassador to Japan, on Capitol Hill in Washington, U.S., May 18, 2017. REUTERS/Yuri Gripas 

U.S. Senate Majority Leader Mitch McConnell (R-KY), left, Senator Lindsey Graham (R-SC), center right, and Senator Ben Cardin (D-MD), right, meet with Iraq Prime Minister Haider al-Abadi, center left, on Capitol Hill in Washington March 21, 2017. REUTERS/James Lawler Duggan 

U.S. Senators (left to right) Joe Donnelly (D-IN), Tammy Duckworth (D-IL), Orrin Hatch (R-UT), Majority Leader Mitch McConnell (R-KY), Lindsey Graham (R-SC), Ben Cardin (D-MD), and Tim Kaine (D-VA) meet with Iraq's Prime Minister Haider al-Abadi, center, on Capitol Hill in Washington March 21, 2017. REUTERS/James Lawler Duggan 

Senator Ben Cardin (D-MD) speaks at a press conference on the need for increased government transparency at the Capitol in Washington, D.C., U.S. March 15, 2017. REUTERS/Aaron P. Bernstein 

Senator Ben Cardin (D-MD) speaks at a press conference on the need for increased government transparency at the Capitol in Washington, D.C., U.S. March 15, 2017. REUTERS/Aaron P. Bernstein 

Israeli Prime Minister Benjamin Netanyahu (C) stands with (L-R) Senators John Barrasso (R-WY), Ben Cardin (D-MD), Bob Casey (D-PA), Senate Minority Leader Chuck Schumer (D-NY), Senate Majority Leader Mitch McConnell (R-KY), Bob Menendez (D-NJ) and John McCain (R-AZ) at the U.S. Capitol in Washington, U.S., February 15, 2017. REUTERS/Joshua Roberts 

German Foreign Minister Sigmar Gabriel (L) and Senate Foreign Relations Committee ranking member Sen. Ben Cardin (D-MD) chat before a meeting on Capitol Hill in Washington, U.S., February 2, 2017. REUTERS/Yuri Gripas 

German Foreign Minister Sigmar Gabriel (L) talks to Senate Foreign Relations Committee ranking member Sen. Ben Cardin (D-MD) before a meeting on Capitol Hill in Washington, U.S., February 2, 2017. REUTERS/Yuri Gripas 

German Foreign Minister Sigmar Gabriel (C) poses with Senate Foreign Relations Committee Chairman Bob Corker (L) (R-TN) and ranking member Sen. Ben Cardin (D-MD) before their meeting on Capitol Hill in Washington, U.S., February 2, 2017. REUTERS/Yuri Gripas 

Sen. Ben Cardin (D-MD) speaks during a rally against President Donald Trump's travel ban outside the Supreme Court in Washington, DC, U.S. January 30, 2017. REUTERS/Aaron P. Bernstein 

Committee chairman U.S. Senator Bob Corker (R-TN) (L) and ranking member Senator Ben Cardin (D-MD) (R) lead the confirmation hearing of Rex Tillerson, the former chairman and chief executive officer of Exxon Mobil, on his nomination to be U.S. secretary of state in Washington, U.S. January 11, 2017. REUTERS/Jonathan Ernst 

Senate Foreign Relations Committee Chairman Bob Corker (L) (R-TN) talks with ranking member Sen. Ben Cardin (D-MD) pror to a Senate Foreign Relations Committee confirmation hearing on Rex Tillerson's nomination to be U.S. secretary of state, on Capitol Hill in Washington, U.S. January 11, 2017. REUTERS/Jonathan Ernst

Rex Tillerson (C), former chairman and chief executive officer of Exxon Mobil, arrives between Senators' Bob Corker (L) (R-TN) and Ben Cardin (2NDR) (D-MD) prior to testifying before a Senate Foreign Relations Committee confirmation hearing on his nomination to be U.S. secretary of state, on Capitol Hill in Washington, U.S. January 11, 2017. REUTERS/Kevin Lamarque

Rex Tillerson (C), former chairman and chief executive officer of Exxon Mobil, arrives between Senators' Bob Corker (L) (R-TN) and Ben Cardin (D-MD) prior to testifying before a Senate Foreign Relations Committee confirmation hearing on his nomination to be U.S. secretary of state, on Capitol Hill in Washington, U.S. January 11, 2017. REUTERS/Kevin Lamarque

Rex Tillerson (C), former chairman and chief executive officer of Exxon Mobil, arrives between Senators' Bob Corker (L) (R-TN) and Ben Cardin (D-MD) prior to testifying before a Senate Foreign Relations Committee confirmation hearing on his nomination to be U.S. secretary of state, on Capitol Hill in Washington, U.S. January 11, 2017. REUTERS/Kevin Lamarque

U.S. Senator-elect Chris Van Hollen (D-MD) (L) and U.S. Senator Ben Cardin (D-MD) arrive for Senate Democratic party leadership elections at the U.S. Capitol in Washington, DC, U.S. November 16, 2016. REUTERS/Jonathan Ernst 

Democratic U.S. presidential candidate Hillary Clinton speaks as U.S. Senators Barbara Mikulski and Ben Cardin and U.S. Rep. Elijah Cummings of Maryland stand behind her during a campaign rally in Baltimore, Maryland April 10, 2016. REUTERS/Jim Bourg 

U.S. Senator Ben Cardin, Maryland, attends the World Climate Change Conference 2015 (COP21) at Le Bourget, near Paris, France, December 5, 2015. REUTERS/Stephane Mahe

U.S. Vice President Joe Biden (2nd L) talks to Justin Ramos (L) and Jayden Ramos (3rd L), the sons of slain New York City police officer Rafael Ramos, after U.S. President Barack Obama (2nd R) signed the Rafael Ramos and Wenjian Liu National Blue Alert Act into law in the Oval Office in Washington May 19, 2015. Ramos and Liu were the New York City police officers shot dead while in a patrol car last December by a killer who said he wanted to kill police in revenge for deaths of black men by police. Also pictured are U.S. Senator Ben Cardin (D-MD) (3rd R) and Representative Dave Reichert (R-WA) (R). REUTERS/Jonathan Ernst 

U.S. President Barack Obama (bottom) addresses lawmakers and family members of slain police officers before signing the Rafael Ramos and Wenjian Liu National Blue Alert Act into law in the Oval Office in Washington May 19, 2015. Ramos and Liu were the New York City police officers shot dead while in a patrol car last December by a killer who said he wanted to kill police in revenge for deaths of black men by police. Also pictured are Vice President Joe Biden (L-R), Jayden Ramos, Maritza Ramos, Senator Ben Cardin (D-MD), Representative Dave Reichert (R-WA), Representative Bill Pascrell (D-NJ) and Wei Tang Liu. REUTERS/Jonathan Ernst 

U.S. President Barack Obama (C) talks to reporters before signing the Rafael Ramos and Wenjian Liu National Blue Alert Act into law, surrounded by lawmakers and family members in the Oval Office in Washington May 19, 2015. Ramos and Liu were the New York City police officers shot dead while in a patrol car last December by a killer who said he wanted to kill police in revenge for deaths of black men by police. Also pictured are Justin Ramos (L-R), Vice President Joe Biden, Jayden Ramos, Maritza Ramos, Senator Ben Cardin (D-MD), Representative Dave Reichert (R-WA), Representative Bill Pascrell (D-NJ), Wei Tang Liu and Xiu Yan Li. REUTERS/Carlos Barria 

U.S. President Barack Obama (bottom) addresses lawmakers and family members of slain police officers before signing the Rafael Ramos and Wenjian Liu National Blue Alert Act into law in the Oval Office in Washington May 19, 2015. Ramos and Liu were the New York City police officers shot dead while in a patrol car last December by a killer who said he wanted to kill police in revenge for deaths of black men by police. Also pictured are Justin Ramos (L-R), Vice President Joe Biden, Jayden Ramos, Maritza Ramos, Senator Ben Cardin (D-MD), Representative Dave Reichert (R-WA), Representative Bill Pascrell (D-NJ) and Wei Tang Liu. REUTERS/Jonathan Ernst 

U.S. President Barack Obama (bottom) addresses lawmakers and family members of slain police officers before signing the Rafael Ramos and Wenjian Liu National Blue Alert Act into law in the Oval Office in Washington May 19, 2015. Ramos and Liu were the New York City police officers shot dead while in a patrol car last December by a killer who said he wanted to kill police in revenge for deaths of black men by police. Also pictured are Jayden Ramos (L-R), Maritza Ramos, Senator Ben Cardin (D-MD), Representative Dave Reichert (R-WA), Representative Bill Pascrell (D-NJ), Wei Tang Liu and Xiu Yan Li. REUTERS/Jonathan Ernst 

U.S. President Barack Obama (C) hugs Maritza Ramos, wife of slain New York City police officer Rafael Ramos, after signing the Rafael Ramos and Wenjian Liu National Blue Alert Act into law in the Oval Office in Washington May 19, 2015. Ramos and Liu were the New York City police officers shot dead while in a patrol car last December by a killer who said he wanted to kill police in revenge for deaths of black men by police. Also pictured are Vice President Joe Biden (L-R), Justin Ramos, Jayden Ramos, Senator Ben Cardin (D-MD) and Representative Dave Reichert (R-WA). REUTERS/Jonathan Ernst 

U.S. President Barack Obama (C) is surrounded by lawmakers and family members of slain police officers as he signs the Rafael Ramos and Wenjian Liu National Blue Alert Act into law in the Oval Office in Washington May 19, 2015. Ramos and Liu were the New York City police officers shot dead while in a patrol car last December by a killer who said he wanted to kill police in revenge for deaths of black men by police. Also pictured are Justin Ramos (L-R), Vice President Joe Biden, Jayden Ramos, Maritza Ramos, Senator Ben Cardin (D-MD), Representative Dave Reichert (R-WA), Representative Bill Pascrell (D-NJ), Wei Tang Liu and Xiu Yan Li. REUTERS/Jonathan Ernst TPX IMAGES OF THE DAY

Britain's Prince Charles (4th L) arrives to meet with members of the U.S. Senate Foreign Relations Committee including Senator Edward Markey (D-MA) (L-R), Senator Cory Gardner (R-CO), Senator Robert Menendez (D-NJ), Senator Tom Udall (D-NM), Senator Johnny Isakson (R-GA), Senator Ben Cardin (D-MD) and Senator Susan Collins (R-ME) at the U.S. Capitol in Washington, March 19 2015. REUTERS/Jonathan Ernst

Britain's Prince Charles (3rd L) poses ahead of a meeting with members of the Senate Foreign Relations Committee at the U.S. Capitol in Washington, DC March 19, 2015. (L to R) Senator Cory Gardner (R-CO), Senator Bob Menendez (D-NJ), Senator Tom Udall (D-NM), Senator Johnny Isakson (D-GA), Senator Ben Cardin (D-MD), and Senator Susan Collins (R-ME). REUTERS/Mandel Ngan/Pool 

Britain's Prince Charles (4th L) poses ahead of a meeting with members of the Senate Foreign Relations Committee at the U.S. Capitol in Washington, DC March 19, 2015. From (L-R) Senator Ed Markey, (D-MA), Senator Cory Gardner (R-CO), Senator Bob Menendez (D-NJ), Senator Tom Udall (D-NM), Senator Johnny Isakson (D-GA) , Senator Ben Cardin (D-MD), Senator Susan Collins (R-ME) and Senator Brian Schatz (D-HI). REUTERS/Mandel Ngan/Pool

Delegates listen to remarks by U.S. Senator Ben Cardin (D-MD) and Senator Lindsey Graham (R-SC) (neither pictured) as they address the American Israel Public Affairs Committee (AIPAC) policy conference in Washington, March 1, 2015. Israeli Prime Benjamin Netanyahu has come under almost unprecedented criticism from the U.S. administration and in Israel for his planned speech to Congress on Tuesday, as international talks with Iran are under way to secure a deal on Teheran's nuclear program. REUTERS/Jonathan Ernst (UNITED STATES - Tags: POLITICS) 

Delegates applaud remarks by U.S. Senator Ben Cardin (D-MD) and Senator Lindsey Graham (R-SC) (neither pictured) as they address the American Israel Public Affairs Committee (AIPAC) policy conference in Washington March 1, 2015. Israeli Prime Benjamin Netanyahu has come under almost unprecedented criticism from the U.S. administration and in Israel for his planned speech to Congress on Tuesday, as international talks with Iran are under way to secure a deal on Teheran's nuclear program. REUTERS/Jonathan Ernst (UNITED STATES - Tags: POLITICS) 

U.S. Senator Ben Cardin (D-MD) (C) and Senator Lindsey Graham (R-SC) (R), interviewed by Director of the School of Media and Public Affairs at George Washington University Frank Sesno (L), address the American Israel Public Affairs Committee (AIPAC) policy conference in Washington, March 1, 2015. Israeli Prime Benjamin Netanyahu has come under almost unprecedented criticism from the U.S. administration and in Israel for his planned speech to Congress on Tuesday, as international talks with Iran are under way to secure a deal on Teheran's nuclear program. REUTERS/Jonathan Ernst (UNITED STATES - Tags: POLITICS) 

Senator Ben Cardin (D-MD) addresses the American Israel Public Affairs Committee (AIPAC) policy conference in Washington March 1, 2015. Israeli Prime Benjamin Netanyahu has come under almost unprecedented criticism from the U.S. administration and in Israel for his planned speech to Congress on Tuesday, as international talks with Iran are under way to secure a deal on Teheran's nuclear program. REUTERS/Jonathan Ernst (UNITED STATES - Tags: POLITICS) 

U.S. Senator Ben Cardin (D-MD) and Senator Lindsey Graham (R-SC) (R) join hands as they take the stage to address the American Israel Public Affairs Committee (AIPAC) policy conference in Washington March 1, 2015. Israeli Prime Benjamin Netanyahu has come under almost unprecedented criticism from the U.S. administration and in Israel for his planned speech to Congress on Tuesday, as international talks with Iran are under way to secure a deal on Teheran's nuclear program. REUTERS/Jonathan Ernst (UNITED STATES - Tags: POLITICS) 

Actors Paul Jesson (R, as Cardinal Wolsey) and Ben Miles (as Thomas Cromwell) perform in an adaptation of Hilary Mantel's books "Wolf Hall" and "Bring Up the Bodies" during a photocall at the Aldwych Theatre in London May 15, 2014. Five centuries after he ruled the political roost in Tudor England, Henry VIII's chief minister Thomas Cromwell is playing to packed houses in London in two plays based on the best-selling novels of Hilary Mantel. It is further evidence of how her double Man Booker prize-winning books "Wolf Hall" and "Bring Up the Bodies", which have sold more than 3 million copies worldwide, resonate for modern audiences with their mix of political and sexual intrigue. Picture taken on May 15. To match story THEATRE-BRITAIN/WOLFHALL REUTERS/Luke MacGregor (BRITAIN - Tags: ENTERTAINMENT SOCIETY) 

Actors Paul Jesson (L, as Cardinal Wolsey) and Ben Miles (as Thomas Cromwell) perform in an adaptation of Hilary Mantel's books "Wolf Hall" and "Bring Up the Bodies" during a photocall at the Aldwych Theatre in London May 15, 2014. Five centuries after he ruled the political roost in Tudor England, Henry VIII's chief minister Thomas Cromwell is playing to packed houses in London in two plays based on the best-selling novels of Hilary Mantel. It is further evidence of how her double Man Booker prize-winning books "Wolf Hall" and "Bring Up the Bodies", which have sold more than 3 million copies worldwide, resonate for modern audiences with their mix of political and sexual intrigue. Picture taken on May 15. To match story THEATRE-BRITAIN/WOLFHALL REUTERS/Luke MacGregor (BRITAIN - Tags: ENTERTAINMENT SOCIETY) 

Pussy Riot punk band members Maria Alyokhina (2nd L, in glasses), Nadya Tolokonnikova (C), Pyotr Verzilov (2nd R), interpreter and husband of Tolokonnikova, U.S. Representative Steve Cohen (D-TN) (L) and Senator Ben Cardin (D-MD) (R) talk to reporters after meeting at the U.S. Capitol in Washington May 6, 2014. REUTERS/Jonathan Ernst (UNITED STATES - Tags: POLITICS) 

U.S. Senator Ben Cardin (D-MD) (at podium), a senior member of the Senator Foreign Relations Committee and Chairman of the U.S. Helsinki Commission, talks to reporters after meeting with Pussy Riot punk band members Maria Alyokhina (2nd R, with eyeglasses) and Nadya Tolokonnikova (R, in red) at the U.S. Capitol in Washington May 6, 2014. REUTERS/Jonathan Ernst (UNITED STATES - Tags: POLITICS) 

U.S. Senator Ben Cardin (D-MD) (obscured by podium), a senior member of the Senator Foreign Relations Committee and Chairman of the U.S. Helsinki Commission, talks to reporters after meeting with Pussy Riot punk band members Maria Alyokhina (2nd R) and Nadya Tolokonnikova (R) at the U.S. Capitol in Washington May 6, 2014. REUTERS/Jonathan Ernst (UNITED STATES - Tags: POLITICS) 

U.S. Senator Ben Cardin (D-MD) (2nd L), a senior member of the Senator Foreign Relations Committee and Chairman of the U.S. Helsinki Commission, talks to reporters after meeting with Pussy Riot punk band members Maria Alyokhina (2nd R) and Nadya Tolokonnikova (R) at the U.S. Capitol in Washington May 6, 2014. REUTERS/Jonathan Ernst (UNITED STATES - Tags: POLITICS) 

(L-R) U.S. Senator Ben Cardin (D-MD), a senior member of the Senator Foreign Relations Committee and Chairman of the U.S. Helsinki Commission, listens as Pussy Riot punk band members Maria Alyokhina and Nadya Tolokonnikova speak to reporters through Pyotr Verzilov (C), interpreter and husband of Tolokonnikova, after meeting at the U.S. Capitol in Washington May 6, 2014. Also pictured is Senator Richard Blumenthal (D-CT). REUTERS/Jonathan Ernst (UNITED STATES - Tags: POLITICS) 

Furloughed federal workers and union members, upset with the Republican-controlled House of Representatives over the current government shutdown, listen at a news conference with U.S. Senator Ben Cardin, Senator Barbara Mikulski, Senator Barbara Boxer and Senator Mark Warner on Capitol Hill in Washington, October 2, 2013. The fight between Democrats and the Republicans over the government's borrowing power is rapidly merging with the standoff over every day funding, which has forced the first government shutdown in 17 years and forced hundreds of thousands of federal employees to take unpaid leave. REUTERS/Jonathan Ernst (UNITED STATES - Tags: POLITICS BUSINESS)