Mr. Trump, the New York developer, reality television host and political provocateur, shows no signs of backing off from his remarks, made during his announcement of a campaign for the White House three weeks ago.

“When Mexico sends its people, they’re not sending their best,” he said then. “They’re sending people that have lots of problems. And they’re bringing those problems with us. They’re bringing drugs, they’re bringing crime. They’re rapists.”

In the days after, there has been a striking absence of public denunciations of Mr. Trump from leading Republican candidates for president and the party’s top officials in Washington. Only last weekend did Jeb Bush — after a muted earlier response — call the “rapists” comment “extraordinarily ugly” and “not reflective of the Republican Party.”

But Mr. Priebus took a quieter route on Wednesday. In a brief telephone conversation with Mr. Trump, first reported by the Washington Post, he urged Mr. Trump to soften his tone on immigrants even as he offered praise of his candidacy, according to Mr. Trump and others told of the conversation.

In classic form, though, Mr. Trump quickly thanked the party chairman with acerbic broadsides that could discourage similar attempts to rein him in. Mr. Trump reached out to a New York Times reporter Thursday morning to say the call was “congratulatory,” not condemnatory, and posit that Mr. Priebus “knows better than to lecture me.”

He added, “We’re not dealing with a five-star Army general.”

Mr. Trump’s language about Mexicans highlighted two of the most divisive issues within the Republican coalition — race and immigration. It was Mr. Priebus who led a bracing review of the party’s 2012 losses, resulting in dire warnings about its need to improve its standing with Hispanics. But Mr. Trump’s support is expected to draw heavily from those disaffected white voters who lined up behind Mitt Romney in 2012 — and whom Republicans acknowledge they will need again to recapture the White House in 2016.