Trump has already met with Mitt Romney, Rick Perry, Herman Cain, Sarah Palin, and Michele BachmannMichele Marie BachmannBachmann won't run for Franken's Senate seat because she did not hear a 'call from God' Billboard from ‘God’ tells Michele Bachmann not to run for Senate Pawlenty opts out of Senate run in Minnesota MORE at least once. Bachmann and Trump have met four times. Each of those candidates has shared time atop national Republican polls, but the race has proven volatile. Gingrich may be hoping that a Trump endorsement could cement his recent rise to the top of the polls and consolidate conservative support.

But Trump warned the party in an interview late last month that he might still enter the presidential fray "if they choose the wrong person."

"If the Republicans, and I've said this to you a number of times, if they choose the wrong person, and the economy will continue to be bad, because we have people who absolutely have no idea what they're doing leading the country, I think it continues to be a possibility," Trump said on "Fox and Friends."