Republican presidential candidate Donald Trump addresses supporters at a rally held at the Sacramento International Jet Center, Wednesday, June 1, 2016, in Sacramento, Calif. (AP Photo/Jae C. Hong) ** FILE **
In this March 1, 2016 file photo, Republican presidential candidate Donald Trump speaks during a campaign stop at the Signature Flight Hangar at Port-Columbus International Airport in Columbus, Ohio. China features prominently in the rhetoric of presumed Republican presidential candidate Donald Trump, who accuses the country of stealing American jobs and cheating at global trade. In China itself, though, hes only now emerging as a public figure, despite a notoriety elsewhere for his voluble utterances, high-profile businesses and reality TV show. (AP Photo/John Minchillo, File)
Supporters and bikers at a Rolling Thunder rally on the National Mall listen to GOP presidential candidate Donald Trump speak. The organization offered an invitation for candidates to speak, but only Mr. Trump accepted.
In this photo provided by ABC, Republican presidential candidate, Donald Trump, left, talks with host Jimmy Kimmel during a taping of the ABC television show, "Jimmy Kimmel Live!,” on Wednesday, May 25, 2016, in Los Angeles. Trump made an appearance as a guest, along with musical guest Greg Porter on the late night show, which airs every weeknight at 11:35 p.m. EST. (Randy Holmes/ABC via AP)
Republican presidential candidate Donald Trump applauds after singing the National Anthem during a rally at the Anaheim Convention Center, Wednesday, May 25, 2016, in Anaheim, Calif. (AP Photo/Jae C. Hong)
FILE - In this April 28, 2016 file photo, Republican presidential candidate Donald Trump speaks during a rally in Costa Mesa, Calif. Police are preparing for the possibility of protests at a Trump rally in Orange County Wednesday, May 25, 2016, after a similar event drew raucous anti-Trump demonstrations that blocked traffic and damaged police cars. (AP Photo/Chris Carlson, File)
Republican presidential candidate Donald Trump speaks during a rally in Spokane, Washington, on Saturday. Mr. Trump has vehemently opposed many of the trade agreements congressional Republicans have supported, and he put tax increases on the table — something congressional Republicans are sure to oppose. (Associated Press)