Trump has dominated political news for two weeks as disparaging remarks he made about Mexican immigrants, labeling them drug runners and rapists, have caused steadily mounting concern among many Republican strategists.
Party officials, who have emphasized a need to reach out to Latino voters, have watched as Trump's comments have threatened to worsen the GOP's already weak image among that growing group of voters. His remarks have divided the GOP presidential candidates and delighted Democratic operatives.
Since the initial remarks he made during his campaign kickoff last month in New York, Trump has escalated his comments in a series of radio and television interviews, claiming that the Mexican government had deliberately sent criminals to the U.S.
Amid deepening concerns from GOP donors, Republican National Committee Chairman
"The chairman had a private conversation with Mr. Trump, as he does with all of our candidates pursuing the nomination," Sean Spicer, RNC chief strategist, said in a statement. "It spanned several areas, including his recent comments about illegal immigration. The call lasted no longer than 20 minutes."
Trump disputed a report of the call that initially appeared in the Washington Post, which said the call had lasted about an hour.
In an interview with the Post on Thursday and later in an interview with Sean Hannity on Fox News, Trump issued a thinly veiled threat that he could run as an independent candidate and pointedly would not commit to supporting the GOP ticket should he fail to win the nomination.
"I would have to see who the nominee is," he said.
"So many people want me to run as an independent, so many people," he told the Post. "Everybody wants me to do it." He added that the "best chance of defeating the Democrats" would be if he were the GOP nominee.
In the Hannity interview, Trump repeated his view that the Mexican government was deliberately sending criminals across the border into the United States.
"They are sending us their criminals. We're not talking about the good - the good people come and they're great people, they're better than good people. I love the Mexican people," he said, according to a transcript released by the network. "They have tremendous spirit, they have tremendous vibrance and life. I love them; I have so many friends. I respect the country of Mexico."
But, he said, the country's "leadership is much smarter than our leadership.... They're killing us at the border."
Trump also sharply criticized former Florida Gov. Jeb Bush, also a presidential candidate, who supports giving some legal status short of citizenship to many of the 11 million immigrants in the country illegally.
"I watch Jeb Bush; he's a joke on immigration," Trump said. Bush "said they come as an act of love - I don't know if you remember his famous it's an 'act of love,'" he said, referring to a remark Bush made in 2014.
"This has nothing to do with love. This is serious stuff," Trump said. "You have very serious situations coming over here and they are taking people that should be in Mexican prisons, Mexican jails and they are pushing them over to the United States. These are dangerous people."
Trump is widely unpopular, with large majorities of Democrats and Republicans viewing him unfavorably, according to recent polls, but he also has an ardent following, and his comments about Mexican immigrants have clearly touched a nerve with some GOP voters.
The response to his remarks intensified after Kathryn Steinle, a 32-year-old strolling San Francisco's Embarcadero, was shot by a Mexican man who was in the country illegally and had previously been deported.
So far, most Republican presidential candidates have been measured in their comments about Trump.
Steve Schmidt, a Republican strategist, said the challenge the party faces with Trump will be a character test for the other candidates vying for the nomination.
"What Trump is saying in public is what thousands of people are shouting at TVs behind closed doors," Schmidt said. "How the presidential candidates engage him, debate him and rebut him will speak volumes about their toughness, political acumen and capacity for leadership."
Both Florida Sen. Marco Rubio, whose parents were Cuban immigrants, and Trump will speak this weekend at FreedomFest in Las Vegas. Nevada, which is an early-voting state, boasts a robust Latino electorate that will influence a general election in the swing state.
Trump then plans to travel to Phoenix, where he is scheduled to speak to Republicans alongside Maricopa County Sheriff
"Donald Trump's views are coarse, ill-informed and inaccurate, and they are not representative of the Republican Party," Flake said in a statement. "As an elected Republican official, I'm disappointed the county party would host a speaker that so damages the party's image."
The Maricopa County Republican Party said Thursday night that it would welcome Trump.
"In Maricopa County we believe deeply in Reagan's eleventh commandment that 'thou shall not speak ill of any other Republican,'" the party said in a statement. "It is disappointing when our Republican leaders do not share that same commitment to party unity and teamwork."