Attorney General Beau Biden (D-DE) (L) and Vice Presidential candidate Senator Joe Biden (D-DE) gesture on stage at the 2008 Democratic National Convention in Denver, Colorado August 27, 2008. U.S. Senator Barack Obama (D-IL) is expected to accept the Democratic presidential nomination at the convention on August 28. REUTERS/Chris Wattie (UNITED STATES) US PRESIDENTIAL ELECTION CAMPAIGN 2008 (USA) 

Delaware Attorney General Beau Biden, son of U.S. Vice President Joe Biden, addresses the final session of the Democratic National Convention in Charlotte, North Carolina September 6, 2012. REUTERS/Jason Reed (UNITED STATES - Tags: POLITICS ELECTIONS)

Attorney General of Delaware Beau Biden addresses the final session of the Democratic National Convention in Charlotte, North Carolina September 6, 2012. REUTERS/Eric Thayer (UNITED STATES - Tags: POLITICS ELECTIONS)

Delaware Attorney General Beau Biden, son of U.S. Vice President Joe Biden gestures before addressing the final session of the Democratic National Convention in Charlotte, North Carolina September 6, 2012. REUTERS/Chris Keane (UNITED STATES - Tags: POLITICS ELECTIONS)

U.S. Vice President Joe Biden (C) takes the oath of office from Supreme Court Justice Sonia Sotomayor as his wife Jill Biden holds the family bible and family members look on at the U.S. Naval Observatory in Washington January 20, 2013. Shown are R. Hunter Biden (front row), Maisy Biden (black cardigan), Noami Biden (red shirt), Finnegan Biden (maroon and black dress), Natalie Biden (front row, purple dress), Kathleen Biden, Hunter Biden, Ashley Biden, Howard Krein, Beau Biden and Hallie Biden REUTERS/Saul Loeb/POOL (UNITED STATES - Tags: POLITICS)

Incumbent Delaware Attorney General Beau Biden talks with a supporter during a campaign event in Newark, Delaware, October 29, 2010. REUTERS/Tim Shaffer (UNITED STATES - Tags: POLITICS ELECTIONS) 

U.S. Vice President Joe Biden walks with his sons Beau (L) and Hunter (2nd R) and his wife Jill down Pennsylvania Avenue during the inaugural parade in Washington January 20, 2009. REUTERS/Larry Downing (UNITED STATES) 

U.S. Vice President Joe Biden (2nd L) waves after being sworn in by Supreme Court Justice John Paul Stevens (R) as the Biden children Beau (2nd R), Hunter (C), and wife Jill Biden (L) watch in Washington January 20, 2009. REUTERS/Jason Reed (UNITED STATES) 

Democratic Vice Presidential nominee U.S. Senator Joe Biden (D-DE) with his son Beau Biden (L) acknowledge the audience at the 2008 Democratic National Convention in Denver, Colorado, August 27, 2008. Democrats nominated Senator Barack Obama (D-IL) on Wednesday as their presidential candidate in a historic first for a black American, sending him into battle against Republican John McCain. REUTERS/Mike Segar (UNITED STATES) US PRESIDENTIAL ELECTION CAMPAIGN 2008 (USA) 

Vice presidential candidate Senator Joe Biden (D-DE) (R) embraces his son, Beau Biden, Attorney General of Delaware after his son introduced him at the 2008 Democratic National Convention in Denver, Colorado, August 27, 2008. U.S. Senator Barack Obama (D-Il) is expected to accept the Democratic presidential nomination at the convention on August 28. REUTERS/Larry Downing (UNITED STATES) US PRESIDENTIAL ELECTION CAMPAIGN 2008 (USA)