Donald Trump -- Thanks For The Endorsement Dana ... I'll Be Watching UFC Tonight

Donald Trump returned the love he got from UFC honcho Dana White -- who endorsed him for Prez on TMZ Sports -- because Trump just told America he's getting in on the Conor McGregor action tonight.

Trump just said he's spending Saturday night in front of the TV, watching McGregor square off with Jose Aldo and Luke Rockhold while they take on Chris Weidman.

Trump and White have been tight for years. Trump -- who owns the Taj Mahal in Atlantic City -- was first to jump on board and host the UFC.