WASHINGTON — Donald Trump on Monday called for a “total and complete shutdown of Muslims entering the United States,” a dramatic escalation of the Republican front-runner’s harsh anti-immigrant rhetoric that drew immediate rebuke from his GOP rivals as well as the White House.
By singling out an entire religious group, Trump seemed to be seeking to capitalize on fears of terrorism in the wake of the San Bernardino, Calif., shooting attack last week by a Muslim couple who FBI officials said Monday had been secretly radicalized for “quite some time.”
He offered no details on how such a policy would work. His campaign said that it would apply to all Muslims, including tourists, trying to enter the United States.
Trump’s presidential primary rivals and other top Republicans — including Massachusetts Governor Charlie Baker, who called it “ridiculous’’ — delivered swift condemnation. Former Florida governor Jeb Bush tweeted that Trump had become “unhinged.’’
Trump framed his demand as a national security concern. His campaign issued a statement late Monday that asserted that there is “great hatred towards Americans by large segments of the Muslim population’’ and proposed sealing the borders against Muslims “until our country’s representatives can figure out what is going on.”
“It is obvious to anybody the hatred is beyond comprehension,” he said in the campaign statement. “Where this hatred comes from and why we will have to determine. Until we are able to determine and understand this problem and the dangerous threat it poses, our country cannot be the victims of horrendous attacks by people that believe only in jihad, and have no sense of reason or respect for human life.”
At a rally in South Carolina Monday night, Trump won cheers as he talked about modifying the Internet to prevent Americans from being radicalized, and said mosques need to receive greater scrutiny (“Something is happening in there — man, there’s anger”).
“We can be politically correct, and we can be stupid,” he said. “But it’s going to get worse and worse.”
Trump’s latest position came a day after President Obama delivered an Oval Office address calling for Americans to distinguish between peaceful Muslims and those who want to inflict violence in the name of holy war. Some Republicans bristled, saying their party had not suggested otherwise. And by Monday evening, there was a clear sense from GOP candidates that they believed Trump has gone too far.
“Donald Trump is unhinged,” Bush wrote on Twitter. “His ‘policy’ proposals are not serious.” South Carolina Senator Lindsey Graham tweeted that Trump “has gone from making absurd comments to being downright dangerous with his bombastic rhetoric.”
“This is the kind of thing that people say when they have no experience and don’t know what they’re talking about,” New Jersey Governor Chris Christie said in an interview with syndicated radio host Michael Medved. “But there are folks in this race who don’t care about what the law says because they’re used to being able to just fire people indiscriminately on television.”
Trump’s campaign did not respond to several questions from the Globe, including how the government would define a Muslim for purposes of entering the country, and whether he would attempt to prohibit American Muslim citizens who are abroad from returning home. He said on Fox News that the policy would not apply to Muslims who are part of the US military, saying, “They’ll come home.”
“This proposal is not only uncivilized and unconstitutional, it has the potential to breed more extremism,” said Qasim Rashid, a fellow at Harvard’s Prince Alwaleed Bin Talal Islamic Studies Program and spokesman for Ahmadiyya Muslim Community USA, the country’s oldest Muslim organization.
Governor Baker, who has generally attempted to stay out of the fray and avoided national Republican politics, sharply criticized Trump.
“First of all, it’s unrealistic. Secondly, it’s inappropriate. And third, it doesn’t make any sense,” Baker said.
After Baker was handed a printout of Trump’s statement, he grew angrier.
“I can’t believe that I’m reading this, which is basically directly in contrast and in conflict with most of the most important values that people in this country hold most dear,” he told reporters at the State House.
Democrat Hillary Clinton, a former secretary of state, called the proposal “reprehensible, prejudiced, and divisive,” while former Maryland governor Martin O’Malley, also a Democrat, said Trump “is running for president as a fascist demagogue.”
Following the attacks in Paris, several Republican candidates have adopted harsher rhetoric, calling for tougher measures targeting Muslims in a way that departs from the tone set after the Sept. 11, 2001, attacks when President George W. Bush made clear that America was at war with terrorists, not with Islam.
Texas Senator Ted Cruz has said that he would allow Christian refugees to enter the United States, but not Muslims. Ben Carson compared admitting Syrian refugees to having “a rabid dog around your neighborhood.”
But Trump has been far more aggressive. Two weeks ago he said that Muslims should be registered in a federal database. He has repeatedly claimed, without firm evidence, that “thousands and thousands” of Muslims were cheering the attacks from Jersey City on Sept. 11, 2001. But he also has said he would be willing to have a Muslim member of his cabinet and has called Muslims “terrific people.”
Trump has often lashed out whenever he starts to slip in the polls, and earlier on Monday a new poll in Iowa showed Trump dropping from his top spot and Cruz surging ahead.
Cruz, when asked on Monday night about Trump’s comments, did not denounce them.
“That is not my policy,” he said, pointing to legislation he’s filed to place a three-year moratorium on refugees from areas controlled by the Islamic State or Al Qaeda.
“We need a commander in chief who is focused on keeping this nation safe,” he said. “And the way to do so is focusing in particular on radical Islamic terrorism, which is exactly what I intend to do.”
Florida Senator Marco Rubio, among the last of the large Republican field to weigh in, said, “I disagree with Donald Trump’s latest proposal. His habit of making offensive and outlandish statements will not bring Americans together.”
A recent poll of New Hampshire voters found 53 percent of Trump supporters favor a national database of Muslims and 49 percent want to shut down US mosques. The same poll, released last week by Public Policy Polling, showed Trump with a comfortable lead.
Joshua Miller of the Globe staff contributed to this report. Matt Viser can be reached at email@example.com. Follow him on Twitter @mviser.