So now Republicans know that hoping it will all go away is not a successful strategy against Donald Trump. That raises a tough question: What, if anything, will work?
The difference between the party's — and its presidential field's — more tentative approach to earlier Trump insults and the near-universal outrage that greeted his demand that all Muslims be barred from entering the country seemed to rest on a sense that Trump has maneuvered from politically disadvantageous territory to a place freighted with danger, whether for the Muslims he is characterizing as threatening or to the United States' strategic imperatives abroad.
Like most of Trump's policy declarations, there was little to explain how he would do it, what the ramifications would be and how exactly it comported with the mores of a nation formed on religious freedom.
That aside, his latest bout of rhetorical exuberance left leading Republicans aghast and many of the party's presidential candidates in a squeeze. They have ignored or halfheartedly waved off insults uttered by Trump since the beginning of his campaign, against such key voter groups as Latinos and women. Even as his past remarks posed the potential of a mammoth problem for the party in 2016, many candidates were disinclined to confront him in any meaningful and persistent way.
Despite Trump's blatant insults, they also promised to support him should he win the nomination.
Jeb Bush, the former Florida governor and possessor of a political lineage that has boomeranged against him this election season, is an example. He bumbled his response to Trump's insults toward Latinos — in one debate, he demanded that Trump apologize to Bush's Mexican-born wife but backed away when Trump refused. This week, he declared Trump was "unhinged." But Bush is still on the record as supporting Trump should the unhinged candidate become the nominee. This as Bush tries to convince Republican voters, in a new television ad, that he alone possesses the backbone to sit in the Oval Office.
As Trump has ascended to the top of public opinion polls this year, he has been fueled by a hyper-charged, shock-driven media environment and his unique skills at salesmanship. But his tactics — us against them — have long been a staple of the nation's political landscape, particularly in times of economic stress and fear. And there has most often been a racial cant to the tactics.
In 1992, when wide swaths of New Hampshire were hobbled by home foreclosures, Republican Pat Buchanan challenged incumbent GOP President George H. W. Bush with the sort of rhetoric familiar to anyone listening to Trump's campaign events.
He said that Jack Kemp, Bush's secretary of Housing and Urban Development, was "down there wearing native garb," a reference to Kemp's efforts to empower minorities. He called Chinese leader Deng Xiaoping "an 85-year-old chain-smoking Communist dwarf." In terminology aimed at Latinos, he said that immigrants who refuse to "assimilate" posed a threat to the United States.
"We are a particular kind of country. We speak the English language," he said.
"People used to come here to become Americans," he added, "but a lot of folks are coming now, in the Southwest, coming to get the benefits of the welfare state."
Buchanan played on turf previously trod by George Wallace, the longtime Alabama governor who fought against racial integration and repeatedly ran for president as a Democrat and, once, as an independent. Wallace's 1972 bid was cut short when he was shot during a campaign event in Maryland.
What Buchanan, Wallace and Trump had in common was a reflexive, strongman appeal to the economically and culturally stressed.
Polls this year repeatedly have shown that Trump is far more popular among those without college educations, a group of Americans who have found it far more difficult to come back from the Great Recession than those more highly educated. Surveys also have shown that Trump's voters are far more driven by opposition to illegal immigration than backers of other candidates.
His voters have little if any regard for the niceties of the GOP establishment, which is perceived as either ignoring or working against their needs.
That sentiment complicates the Republican response now. Dismissing Trump hasn't served to defeat him, but neither will communal denunciations, at least where most of Trump's supporters are concerned.
In interviews with respondents to a September USC Dornsife/Los Angeles Times poll, Trump supporters emotionally expressed their fear at plummeting down the economic ladder, without much of a government handhold to stop their decline. They also acknowledged that they didn't think everything the candidate said was true, or even necessarily wise.
Nor did they care: He was talking to and for them, a rarity in a political structure that's focused on rich donors and the middle class these voters felt was beyond their grasp.
"He might not be a 10 billionaire, whatever he claims to be, but it doesn't matter to me," one Trump supporter said in an interview after the poll found his candidate leading among California Republicans, as he did nationally.
"What matters is what I am hearing regarding an issue that is deep, deep into the U.S. … and nobody is doing anything about it. It's important to me to see someone in an administration doing something."
At the time, those under fire from Trump were Latinos in the country illegally. Now, it is Muslims. If Donald Trump's presidential ambitions persist, the betting is that soon it will be someone else.