Democratic U.S. presidential candidate Hillary Clinton departs a discussion on national security during a campaign stop at the Virginia Air and Space Center in Hampton, Virginia, U.S., June 15, 2016. REUTERS/Gary Cameron 

Democratic U.S. presidential candidate Hillary Clinton departs a discussion on national security during a campaign stop at the Virginia Air and Space Center in Hampton, Virginia, U.S., June 15, 2016. REUTERS/Gary Cameron 

U.S. Democratic presidential candidate Hillary Clinton speaks during a campaign stop in Long Beach, California, United States June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton waves to supporters in the crowd during a campaign stop in Long Beach, California, United States June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton speaks during a campaign stop in Long Beach, California, United States June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton speaks during a campaign stop in Long Beach, California, United States June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton arrives at a campaign stop in Long Beach, California, United States June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton gestures during a campaign stop at a community center in Compton, California, United States June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton gives a thumbs-up during a campaign stop and speech in Los Angeles, California, United States June 6, 2016. REUTERS/Mike Blake. TPX IMAGES OF THE DAY

U.S. Democratic presidential candidate Hillary Clinton helps raise the arms of congresswoman Maxine Waters (R) along with mothers who had lost their sons to police violence, during a campaign stop in Los Angeles, California, United States June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton waves to bye-standers as she departs a lunchtime campaign stop at Hawkins House of Burgers restaurant in Watts, California, United States, June 6, 2016. REUTERS/Mike Blake TPX IMAGES OF THE DAY 

U.S. Democratic presidential candidate Hillary Clinton makes a campaign stop and speech in Los Angeles, California, United States June 6, 2016. REUTERS/Mike Blak 

U.S. Democratic presidential candidate Hillary Clinton gives a thumbs-up during a campaign stop and speech in Los Angeles, California, United States June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton makes a campaign stop in Los Angeles, California, United States June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton makes a campaign stop and speech in Los Angeles, California, United States June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton makes a speech during a campaign stop in Lynwood, California, United States June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton makes a speech during a campaign stop in Lynwood, California, United States June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton makes a speech during a campaign stop in Lynwood, California, United States June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton arrives at a campaign stop in Lynwood, California, United States June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton makes a lunchtime campaign stop at Hawkins House of Burgers restaurant in Watts, California, United States, June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton makes a campaign stop for lunch at Hawkins House of Burgers in Watts, a section of Los Angeles, California, United States June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton waves to bye-standers as she departs a lunchtime campaign stop at Hawkins House of Burgers restaurant in Watts, California, United States, June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton waves to staff while making a lunchtime campaign stop at Hawkins House of Burgers restaurant in Watts, California, United States, June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton makes a speech during a campaign stop in Lynwood, California, United States June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton makes a speech during a campaign stop in Lynwood, California, United States June 6, 2016. REUTERS/Mike Blake

Demi Gibson, who works the order counter at Hawkins House of Burgers shakes hands with U.S. Democratic president candidate Hillary Clinton who made a lunchtime campaign stop a the restaurant in Watts, California, United States June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton makes a speech during a campaign stop in Lynwood, California, United States, June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton makes a speech during a campaign stop in Lynwood, California, United States, June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton arrives at a campaign stop in Lynwood, California, United States, June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton arrives at a campaign stop in Lynwood, California, United States, June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton gives a thumbs-up during a campaign stop at a community center in Compton, California, United States June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton gives a thumbs-up during a campaign stop at a community center in Compton, California, United States June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton makes a campaign stop at a community center in Compton, California, United States June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton makes a campaign stop at a community center in Compton, California, United States June 6, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton gives a thumbs-up during a campaign stop at a community center in Compton, California, United States June 6, 2016. REUTERS/Mike Blake TPX IMAGES OF THE DAY

U.S. Democratic presidential candidate Hillary Clinton arrives on stage as she arrives for a campaign stop in Sacramento, California, United States June 5, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton makes a campaign stop in Sacramento, California, United States June 5, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton holds up the hand of congresswoman Doris Matsui during a campaign stop in Sacramento, California, United States June 5, 2016. REUTERS/Mike Blake

Secret Service agents surround U.S. Democratic presidential candidate Hillary Clinton makes a campaign stop in Sacramento, California, United States June 5, 2016. REUTERS/Mike Blake

Alexa Bauer (5) looks up as U.S. Democratic presidential candidate Hillary Clinton greets supporters after making a speech during a campaign stop in Sacramento, California, United States June 5, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton greets Alexa Bauer (5) after making a speech during a campaign stop in Sacramento, California, United States June 5, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton waves as she sits down to talk during a campaign stop at a small restaurant in Vallejo, California, United States June 5, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton waves as she sits down to talk during a campaign stop at a small restaurant in Vallejo, California, United States June 5, 2016. REUTERS/Mike Blake

Long time aid to U.S. Democratic presidential candidate Hillary Clinton, Huma Abedin, waits in the wings as Clinton makes a campaign stop in Fresno, California, United States June 4, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton arrives at a campaign stop in Fresno, California, United States June 4, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton makes a campaign stop in Fresno, California, United States June 4, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton greets supporters as she makes a campaign stop in Fresno, California, United States June 4, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton waves to the crowd after being introduced by congresswoman Julia Brownley during a campaign stop at a high school in Oxnard, California, United States June 4, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton waves to the crowd as she makes a campaign stop at a high school in Oxnard, California, United States June 4, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton speaks during campaign stop at a high school in Oxnard, California, United States June 4, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton pauses as she speaks at a community college during a campaign stop in Sylmar, California, United States June 4, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton pauses as she speaks at a community college during a campaign stop in Sylmar, California, United States June 4, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton waves with congressman Pete Aguilar as she makes a campaign stop in San Bernadino, California, United States June 3, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton speaks during a campaign stop in San Bernadino, California, United States June 3, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton speaks during a campaign stop in San Bernadino, California, United States June 3, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton arrives at a campaign stop in San Bernadino, California, United States June 3, 2016. REUTERS/Mike Blake

Supporters cheer on U.S. Democratic presidential candidate Hillary Clinton as she speaks at a campaign stop in San Bernardino, California, United States June 3, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton gives a thumbs-up to supporters during a campaign stop in San Bernardino, California, United States June 3, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton waves to supporters during a campaign stop in San Bernardino, California, United States June 3, 2016. REUTERS/Mike Blake

U.S. Democratic presidential candidate Hillary Clinton arrives at a campaign stop in San Bernardino, California, United States June 3, 2016. REUTERS/Mike Blake