What’s more, Mr. Trump’s pitchfork populism doesn’t hold the same visceral appeal for a religious community with above-average education levels, relatively stable families and comfortable middle-class incomes. The urgency to “Make America Great Again” may not be quite so deeply felt.

With the primaries over, most anti-Trump conservatives have abandoned any righteous resistance and begun their dutiful trudge toward supporting the party’s nominee. But there are signs that Mormons — who represent the most reliably Republican religious group in the country — may not fall in line so easily.

In Utah, a deep-red state that no Democrat has won since Lyndon B. Johnson in 1964, a recent poll shows Mr. Trump and Hillary Clinton running neck and neck, with the Libertarian candidate Gary Johnson — who has his campaign headquarters in Salt Lake City — picking up 16 percent, and nearly one-third of despairing respondents opting for “other.” (For perspective, George W. Bush won the state with 71 percent of the vote in 2004.)

Even if Utah ultimately submits to the pull of partisanship as expected, it remains an open question whether Mormons at large will stay engaged in the process. In an expansive Gallup report released last month, none of the 62 demographic groups surveyed were more ambivalent toward both presumptive nominees than Mormons were: Just 33 percent had a favorable view of Mr. Trump; for Mrs. Clinton, it was 21 percent. Such disillusionment could have consequences. The Mountain West has emerged as a general-election battleground in recent years, with explosive Latino growth and other demographic trends turning states that once leaned Republican, like Nevada and Colorado, into November tossups. And in the scrambled electoral map of 2016, Arizona looks increasingly as if it will be in play.

While Mormons make up only about 3 percent to 6 percent of the population in these states, the G.O.P. counts on them. They have high turnout and a reputation in campaign circles as top-notch canvassers unafraid of knocking on strangers’ doors. Their tightly networked communities constitute a reliable political fund-raising apparatus, thanks to the Romney campaign. In states like Colorado — which President Obama won in 2012 by fewer than 120,000 votes — the last thing Republicans need is for Trump-averse Mormons to sit this race out.

It’s entirely possible that, in the end, conservative Mormons will dutifully show up on Election Day and pull the lesser-of-two-evils lever for Mr. Trump. But until then, Mitt Romney has made clear he’ll continue to speak out against his party’s nominee — and many of his coreligionists will be listening. As he told The Wall Street Journal last month, “There are some people, though it’s a small number, who still value my opinion.”