Later in the evening, a surprise speaker will take the stage in support of Mitt Romney and Paul RyanPaul RyanSamantha Bee roasts Trump, media at mock correspondents' dinner Ryan's home state highlights challenge for GOP high-risk insurer pools Trump 'disappointed' in congressional GOP MORE — there is heavy speculation that the speaker will be actor, director and former Carmel, Calif., mayor Clint Eastwood, but the GOP had not confirmed that as of early Thursday morning.

Finally, Sen. Marco RubioMarco RubioOvernight Defense: Commander calls North Korea crisis 'worst' he's seen | Trump signs VA order | Dems push Trump to fill national security posts What’s with Trump’s spelling mistakes? Boeing must be stopped from doing business with Iran MORE (Fla.), who was seen as a potential running mate for Romney, will introduce the presumed nominee, who will officially accept the nomination and close out the convention.