U.S. Democratic presidential candidate Hillary Clinton (C) sits with diners at The Union Diner campaign event in Laconia, New Hampshire, September 17, 2015. REUTERS/Faith Ninivaggi TPX IMAGES OF THE DAY - RTS1MDG

Democratic U.S. presidential candidate Hillary Clinton and Senator Bernie Sanders embrace during a campaign rally where Sanders endorsed Clinton in Portsmouth, New Hampshire, U.S., July 12, 2016. REUTERS/Mary Schwalm - RTSHLLL

Democratic presidential candidate Hillary Clinton leaves a campaign rally with her husband former President Bill Clinton in Des Moines, Iowa, October 24, 2015. REUTERS/Scott Morgan TPX IMAGES OF THE DAY - RTX1T2KE

U.S. Democratic presidential candidate Hillary Clinton campaigns at Rutgers University's Newark campus in Newark, New Jersey, U.S., June 1, 2016. REUTERS/Adrees Latif TPX IMAGES OF THE DAY - RTX2F7PI

U.S. Democratic presidential candidate Hillary Clinton and her husband, former U.S. President Bill Clinton eat breakfast at the Chez Vachon restaurant in Manchester, New Hampshire February 8, 2016. REUTERS/Brian Snyder - RTX260DC

Democratic U.S. presidential candidate Hillary Clinton (L) arrives with Nevada State Assemblyman Nelson Araujo to purchase ice cream between campaign events in North Las Vegas, Nevada October 14, 2015. REUTERS/David Becker TPX IMAGES OF THE DAY - RTS4IRW

U.S. Democratic presidential candidate Hillary Clinton waits backstage at a rally with campaign volunteers in Charlotte, North Carolina, U.S. July 25, 2016. REUTERS/Brian Snyder - RTSJKLQ

Democratic U.S. presidential candidate Hillary Clinton reacts as rival candidate Senator Bernie Sanders (R) tries to hand her a piece of paper during a Democratic debate hosted by CNN and New York One at the Brooklyn Navy Yard in New York April 14, 2016. REUTERS/Lucas Jackson

Democratic U.S. presidential candidate Hillary Clinton (R) after being introduced by US Senator Elizabeth Warren at a campaign rally in Cincinnati, Ohio, U.S. June 27, 2016. REUTERS/Aaron Josefczyk - RTX2IHQ0

Attendees listen to U.S. Democratic presidential candidate Hillary Clinton at a campaign event in Iowa City, Iowa, United States, January 21, 2016. REUTERS/Jim Young - RTX23GWD

Democratic U.S. presidential candidate Hillary Clinton arrives to speak during her California primary night rally held in the Brooklyn borough of New York, U.S., June 7, 2016. REUTERS/Lucas Jackson TPX IMAGES OF THE DAY - RTSGHIR

U.S. Democratic presidential candidate Hillary Clinton greets Louie Dixon as she campaigns at the Iowa State Fair in Des Moines, Iowa, United States, August 15, 2015. REUTERS/Jim Young TPX IMAGES OF THE DAY - RTX1ODUU

Democratic U.S. Presidential candidate Hillary Clinton tours Munster Steel in Hammond, Indiana, United States, April 26, 2016. REUTERS/Jim Young TPX IMAGES OF THE DAY - RTX2BSGM

U.S. Democratic presidential candidate Hillary Clinton takes the stage for a campaign speech outside the shuttered Trump Plaza in Atlantic City, New Jersey July 6, 2016. REUTERS/Brian Snyder - RTX2K0CO

Democratic U.S. Presidential candidate Hillary Clinton talks on the phone at a Dunkin' Donuts coffee shop during a campaign stop in West Palm Beach, Florida March 15, 2016. REUTERS/Carlos Barria - RTSALDV

Democratic U.S. presidential candidate Hillary Clinton listens to her running-mate, Democratic U.S. vice presidential candidate Senator Tim Kaine (D-VA), after she introduced him during a campaign rally in Miami, Florida, U.S. July 23, 2016.

Democratic U.S. presidential candidate Hillary Clinton stands beneath a banner as she is introduced before addressing the 2015 National Immigrant Integration Conference in the Brooklyn borough of New York City, December 14, 2015. REUTERS/Mike Segar - RTX1YOV7

U.S. Democratic presidential candidate Hillary Clinton poses for a group picture on stage during an appearance at a "Women for Hillary" event in Culver City, California, United States, June 3, 2016. REUTERS/Mike Blake TPX IMAGES OF THE DAY - RTX2FL2X

U.S. Democratic presidential candidate Hillary Clinton politely declines to eat more cake samples, after having tried the coconut pound cake and purchasing items to go from Saffron Cafe and Bakery owner Ali Rahnamoon as she greets people at his cafe in Charleston, South Carolina February 26, 2016. REUTERS/Jonathan Ernst TPX IMAGES OF THE DAY - RTX28QYA

U.S. Democratic presidential candidate Hillary Clinton (C) rides the New York City Subway with Bronx Borough President Ruben Diaz (L) in the Bronx borough of New York, April 7, 2016. REUTERS/Brendan McDermid TPX IMAGES OF THE DAY - RTSE18E

U.S. Democratic presidential candidate Hillary Clinton waves to the crowd after delivering her "official launch speech" at a campaign kick off rally in Franklin D. Roosevelt Four Freedoms Park on Roosevelt Island in New York City, June 13, 2015. REUTERS/Lucas Jackson TPX IMAGES OF THE DAY - RTX1GD6T

Democratic U.S. presidential candidate Hillary Clinton speaks at a campaign event in the borough of Staten Island in New York City, April 17, 2016. REUTERS/Brendan McDermid TPX IMAGES OF THE DAY - RTX2ADT9

U.S. Democratic presidential candidate Hillary Clinton waves to someone in the crowd after delivering a speech on national security in San Diego, California, United States June 2, 2016. REUTERS/Mike Blake TPX IMAGES OF THE DAY - RTX2FEN7

U.S. Democratic presidential candidate Hillary Clinton greets supporters after a town hall meeting at Cumberland United Methodist Church in Florence, South Carolina February 25, 2016. REUTERS/Jonathan Ernst TPX IMAGES OF THE DAY - RTX28N1O

Democratic U.S. presidential candidate Hillary Clinton receives a kiss from former U.S. Representative Gabby Giffords on stage at a "Women for Hillary" campaign rally in the Manhattan borough of New York City, U.S. April 18, 2016. REUTERS/Mike Segar TPX IMAGES OF THE DAY - RTX2AJKH

U.S. Democratic presidential candidate Hillary Clinton reacts to reporters' questions as she exits the hearing room for a lunch break from testimony before the House Select Committee on Benghazi on Capitol Hill in Washington October 22, 2015. The congressional committee is investigating the deadly 2012 attack on the U.S. diplomatic mission in Benghazi, Libya, when Clinton was the secretary of state. REUTERS/Gary Cameron TPX IMAGES OF THE DAY - RTS5QKG

U.S. Democratic presidential candidate Hillary Clinton adjusts her make-up before speaking at the Iowa Democratic Party's Hall of Fame dinner in Cedar Rapids, Iowa, United States, July 17, 2015. REUTERS/Jim Young TPX IMAGES OF THE DAY - RTX1KS65

U.S. President Barack Obama points to Democratic U.S. presidential candidate Hillary Clinton during a Clinton campaign event in Charlotte, North Carolina, U.S., July 5, 2016. REUTERS/Brian Snyder - RTX2JVEC