Republican U.S. presidential nominee Donald Trump and Democratic U.S. presidential nominee Hillary Clinton look on at the start of their first presidential debate at Hofstra University in Hempstead, New York, U.S., September 26, 2016. REUTERS/Brian Snyder

Republican U.S. presidential nominee Donald Trump speaks during his first presidential debate against Democratic U.S. presidential nominee Hillary Clinton (not shown) at Hofstra University in Hempstead, New York, U.S., September 26, 2016. REUTERS/Brian Snyder - RTSPKK5

Republican U.S. presidential nominee Donald Trump and Democratic U.S. presidential nominee Hillary Clinton walk away from their podiums at the conclusion of their first presidential debate at Hofstra University in Hempstead, New York, U.S., September 26, 2016. REUTERS/Joe Raedle/Pool - RTSPKQG

Republican U.S. presidential nominee Donald Trump speaks during the first debate with Democratic U.S. presidential nominee Hillary Clinton at Hofstra University in Hempstead, New York, U.S., September 26, 2016. REUTERS/Lucas Jackson - RTSPKGE

Democratic U.S. presidential nominee Hillary Clinton greets moderator Lester Holt (L) as Republican U.S. presidential nominee Donald Trump looks on at the end of their first presidential debate at Hofstra University in Hempstead, New York, U.S., September 26, 2016. REUTERS/Mike Segar - RTSPKQ9

Democratic U.S. presidential nominee Hillary Clinton waves after the first presidential debate against Republican U.S. presidential nominee Donald Trump (not shown) at Hofstra University in Hempstead, New York, U.S., September 26, 2016. REUTERS/Adrees Latif - RTSPKR6

Republican U.S. presidential nominee Donald Trump shakes hands with Democratic U.S. presidential nominee Hillary Clinton at the start of their first presidential debate at Hofstra University in Hempstead, New York, U.S., September 26, 2016. REUTERS/Joe Raedle/Pool

Republican U.S. presidential nominee Donald Trump and Democratic U.S. presidential nominee Hillary Clinton greet one another as they take the stage for their first debate at Hofstra University in Hempstead, New York, U.S. September 26, 2016. REUTERS/Jonathan Ernst - RTSPKDA

Melania (L) and Ivanka (C) Trump sit next to Republican vice presidential nominee Governor Mike Pence (R) ahead of the start of the first debate between Republican U.S. presidential nominee Donald Trump and Democratic U.S. presidential nominee Hillary Clinton at Hofstra University in Hempstead, New York, U.S., September 26, 2016. REUTERS/Joe Raedle/Pool - RTSPK8W

Democratic U.S. presidential nominee Hillary Clinton speaks during her first presidential debate against Republican U.S. presidential nominee Donald Trump (not shown) at Hofstra University in Hempstead, New York, U.S., September 26, 2016. REUTERS/Mike Segar - RTSPKCE

Republican U.S. presidential nominee Donald Trump speaks as Democratic U.S. presidential nominee Hillary Clinton listens during their first presidential debate at Hofstra University in Hempstead, New York, U.S., September 26, 2016. REUTERS/Pool TPX IMAGES OF THE DAY - RTSPKFI

Democratic U.S. presidential nominee Hillary Clinton reacts to comments during the first presidential debate with Republican U.S. presidential nominee Donald Trump at Hofstra University in Hempstead, New York, U.S., September 26, 2016. REUTERS/Lucas Jackson - RTSPKK7

Republican U.S. presidential nominee Donald Trump speaks as Democratic U.S. presidential nominee Hillary Clinton listens during their first presidential debate at Hofstra University in Hempstead, New York, U.S., September 26, 2016. REUTERS/Rick Wilking - RTSPKQH

Democratic U.S. presidential nominee Hillary Clinton holds hands with her husband, former President Bill Clinton, as they leave the stage after the conclusion of the first debate with Republican U.S. presidential nominee Donald Trump at Hofstra University in Hempstead, New York, U.S., September 26, 2016. REUTERS/Joe Raedle/Pool - RTSPKTN

Former U.S. President Bill Clinton (C) talks with his daughter Chelsea Clinton prior to the first presidential debate between Republican presidential nominee Donald Trump and U.S. Democratic presidential candidate Hillary Clinton at Hofstra University in Hempstead, New York, U.S., September 26, 2016. At right is Marc Mezvinsky, the husband of Chelsea Clinton. REUTERS/Carlos Barria - RTSPKD0

Republican U.S. presidential nominee Donald Trump pauses during the first debate with Democratic U.S. presidential nominee Hillary Clinton at Hofstra University in Hempstead, New York, U.S., September 26, 2016. REUTERS/Lucas Jackson - RTSPKJ3

Republican U.S. presidential nominee Donald Trump shakes hands with Democratic U.S. presidential nominee Hillary Clinton at the conclusion of their first presidential debate at Hofstra University in Hempstead, New York, U.S., September 26, 2016. REUTERS/Lucas Jackson

Republican U.S. presidential nominee Donald Trump greets his wife Melania onstage after the conclusion of his first debate with Democratic U.S. presidential nominee Hillary Clinton at Hofstra University in Hempstead, New York, U.S., September 26, 2016. REUTERS/Joe Raedle/Pool - RTSPKRT

Republican U.S. presidential nominee Donald Trump's children Donald Trump Jr., Eric Trump and Tiffany Trump sit together for their father's first debate against Democratic U.S. presidential nominee Hillary Clinton at Hofstra University in Hempstead, New York, U.S. September 26, 2016. REUTERS/Jonathan Ernst - RTSPKK9

Republican U.S. presidential nominee Donald Trump shakes hands with Democratic U.S. presidential nominee Hillary Clinton at the conclusion of their first presidential debate at Hofstra University in Hempstead, New York, U.S., September 26, 2016. REUTERS/Mike Segar TPX IMAGES OF THE DAY - RTSPKQT

Republican U.S. presidential nominee Donald Trump and Democratic U.S. presidential nominee Hillary Clinton walk to their podiums at the start of their first presidential debate at Hofstra University in Hempstead, New York, U.S., September 26, 2016. REUTERS/Rick Wilking - RTSPKB4

Republican U.S. presidential nominee Donald Trump and Democratic U.S. presidential nominee Hillary Clinton discuss a point during their first presidential debate at Hofstra University in Hempstead, New York, U.S., September 26, 2016. REUTERS/Rick Wilking - RTSPKEI

Republican U.S. presidential nominee Donald Trump talks to reporters in the spin room after his first debate against Democratic U.S. presidential nominee Hillary Clinton at Hofstra University in Hempstead, New York, U.S. September 26, 2016. REUTERS/Jonathan Ernst - RTSPKVC

(L-R), Democratic National Committee Chair Donna Brazile, businessman Vernon Jordan, former President Bill Clinton and Chelsea Clinton watch the first presidential debate between Republican U.S. presidential nominee Donald Trump and Democratic U.S. presidential nominee Hillary Clinton at Hofstra University in Hempstead, New York, U.S., September 26, 2016. REUTERS/Pool - RTSPKFV

Republican U.S. presidential nominee Donald Trump reacts during the first presidential debate with Democratic U.S. presidential nominee Hillary Clinton at Hofstra University in Hempstead, New York, U.S., September 26, 2016. REUTERS/Lucas Jackson - RTSPKNN

Republican U.S. presidential nominee Donald Trump speaks as Democratic U.S. presidential nominee Hillary Clinton listens during their first presidential debate at Hofstra University in Hempstead, New York, U.S., September 26, 2016. REUTERS/Rick Wilking - RTSPKBG

Republican U.S. presidential nominee Donald Trump sips water during his first debate with Democratic U.S. presidential nominee Hillary Clinton at Hofstra University in Hempstead, New York, U.S., September 26, 2016. REUTERS/Joe Raedle/Pool - RTSPKCF

Republican U.S. presidential nominee Donald Trump (2nd from L) chats with members of his family after the conclusion of his first debate with Democratic U.S. presidential nominee Hillary Clinton at Hofstra University in Hempstead, New York, U.S., September 26, 2016. REUTERS/Adrees Latif - RTSPKR5