WASHINGTON (AP) — Donald Trump has been trying hard lately to act more presidential and should keep meeting individually with Republican leaders to win the party's trust, the GOP chairman said Friday.

In a brief interview with The Associated Press, Reince Priebus also expressed uncertainty about whether the party's presumptive presidential nominee needs to heal his frosty relationship with House Speaker Paul Ryan before the GOP launches fall campaigns to capture the White House and defend its control of Congress. Ryan, the top Republican in Congress, has declined to endorse Trump, though the two men met privately Thursday in a session both said was positive.

"I'm not sure," Priebus of the need for a Trump-Ryan embrace. But he added, "I do think that Donald Trump understands, and I certainly understand and believe, that the more unity we have, the better off we're going to be."

The extraordinary chasm between the country's two leading Republicans reflects ideological differences over spending, immigration and other issues. In addition, swing district GOP lawmakers worry that Trump's hard-line statements on Hispanics and comments about women's appearances will imperil their re-election prospects.

Priebus, who attended Thursday's meeting between Trump and Ryan, said the session "was more Midwest than New York" and said he believes Ryan will end up chairing the party's July national convention in Cleveland. Trump had threatened to keep Ryan from that largely ceremonial role but has since backtracked.

Priebus repeatedly referred to the problems political professionals have had assessing Trump's candidacy, saying people have been "completely wrong about Donald Trump and the playbook."

Trump seems all but certain to formally become the GOP nominee at the party's convention, despite his insulting entire voting blocs and personal invectives against many of his rivals.

"He's been trying very hard to be presidential and gracious and I think he's actually done a nice job of that lately," Priebus said of Trump, "And I expect him to continue working at it and getting the job done."

To win over Republicans who continue resisting his candidacy, Trump should continue visiting party leaders, Priebus said. Trump also met Thursday with other House GOP leaders and with top Senate Republicans.

"Obviously he's a salesman. So he's naturally talented, and I think the more he does that individually here with leaders of our party, the better off I think he's going to be," Priebus said.

Sidestepping a fresh dispute, Priebus said it is up to Trump and the public whether the billionaire should release his tax returns. Trump refused Friday to reveal even the tax rate he pays, saying he would not do so until the IRS finishes auditing his returns.

Priebus also said he didn't know what to make of a report in The Washington Post that Trump posed as his own spokesman more than two decades ago in phone conversations with reporters in which he provided details about the New York businessman's personal relationships.

The Post posted online a recording of one such phone call from 1991. On NBC's "Today" show Friday, Trump denied the voice was his.

"I don't know if it's true or not, so I don't know what to tell you," Priebus said.

Asked about Trump's departure from GOP orthodoxy on some issues — such as his opposition to trade treaties and to culling savings from big benefit programs like Medicare — Priebus downplayed the differences. Conservatives have been threatening to battle Trump over the GOP platform at the Cleveland convention if he tries altering crucial party principles.

"I don't think Donald Trump is interested in rewriting the platform of the Republican Party," said Priebus. He said "80 to 95 percent of the things he believes in are in line with our platform, and no candidate has been totally in line with our platform."