Donald Trump has a different persona in private than he does in public and he'll shift his personality to appeal to women, minorities and other voters in a general election, his top aide told a meeting of the Republican National Committee on Thursday.

“When he's sitting in a room, he's talking business, he's talking politics in a private room, it's a different persona,” top Trump aide Paul Manafort said during the meeting, a recording of which was obtained by NBC News. “When he's out on the stage, when he's talking about the kinds of things he's talking about on the stump, he's projecting an image that's for that purpose.”

Manafort's comments come as Trump is trying to build a more professional campaign that can lock up the 1,237 delegates needed to win a majority at the Cleveland convention. But they're potentially problematic for a candidate who's built a brand centered on telling it like it is and accusing typical politicians of misleading voters.

In the meeting, Manafort cast Trump as playing a part aimed at winning over his core supporters.

“He [Trump] gets it,” Manafort said, and “the part that he's been playing is evolving into the part that now you've been expecting, but he wasn't ready for because he had to first feed the first phase.”

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Manafort insisted that Trump’s deep unpopularity nationwide, fueled by months of unapologetic bluster on the campaign trail, would be easily remedied when the candidate shifts gears. In contrast, Hillary Clinton’s negatives are character driven and baked-in, Manafort argued.

“The negatives will come down, the image is going to change, but Clinton is still going to be ‘Crooked Hillary,’ and that's what you're going to be seeing a lot more of.”

He also reassured RNC members that Trump will raise money for the party -- something he's so far avoided doing, Manafort said, because it would violate a campaign promise not to take donations.

"He's actually living his word, and that's what the base that we are attracting to the Trump campaign is looking for. They're looking for honesty, and they're looking for consistency, and they're looking for someone who does exactly what they say," Manafort said.

Manafort did assure the RNC that Trump has told him and another top aide, Rick Wiley, that the billionaire will spend what it takes to lock up the nomination before Cleveland.

"He's told Rick and I that he's willing to spend what's necessary to finish this out. That's a big statement from him," Manafort said. "It allows us to put a plan together so that we can make sure that we finish this thing early enough so that you can feel comfortable that he's going to be the nominee."

The meeting represented the Trump campaign’s first pitch to the full RNC membership, who were gathered in Hollywood, Fla. for the party’s Spring Meeting. Sen. Ted Cruz and Ohio Gov. John Kasich both made personal pitches to the 168 party leaders in attendance, while Trump sent Manafort, Political Director Rick Wiley and Ben Carson, a former opponent who’s now one of his more prominent surrogates, on his behalf.

And it came as relations between Trump and the party leadership remain strained, as the candidate has railed against the GOP brass in recent weeks for a nominating process he’s decried as “rigged” and “corrupt.”

But as he moves closer to the nomination, the candidate has made some efforts to mend fences with GOP leaders and prove he can be a viable general election candidate, bringing on a team of seasoned new advisers and promising to moderate his tone and message on the trail.

Trump’s aides aides have pledged voters will see a more presidential Trump on the campaign trail going forward, and the idea of “two Trumps” is not new — Carson said he had seen two different Trumps when he announced his endorsement of the candidate. Manafort made the case that Trump has put on his past “persona” to prove he could win elections and gain credibility with the party.

“The campaign model he put together, and the reason he hasn't been with you all yet, is a model of going out to the voters, and speaking to voters, and looking at winning states, looking to build his credibility, and so he had to prove that he could win elections,” he said.

NBC News' Elyse Perlmutter-Gumbiner contributed to this report.