From his opening slur against Mexicans to his current coddling of the Ku Klux Klan, Donald Trump has shaped the Republican presidential race into a character test for conservatives. For months too many of the country’s most prominent figures on the right have failed to respond adequately to the threat he embodies. Yet now, as Trump seems favored to clinch the GOP nomination, a growing cohort of principled Republicans is forthrightly proclaiming #NeverTrump – and placing country and Constitution above narrow partisanship.

It may be too late to save the Grand Old Party from the extremist contamination that Trump represents, but it is never too late to stand on principle.

Many Republicans have opposed Trump all along, of course, while supporting one or another alternative on the party’s overcrowded debate stage. The casino mogul was too vulgar, too inexperienced, too empty, too populist, or simply too compromised by his long record of contradictory political positions and alliances. Back when all of the Republican presidential candidates signed that pledge to support the eventual nominee, however, uniting the party behind Trump still seemed possible. They didn’t trust him, but they might have supported him anyway in order to win back the White House.

That tempting path is no longer open for any honorable conservative – and fortunately for America, there seems to be quite an assortment of them, including Senator Ben Sasse (R-NE), Washington Post columnist Jennifer Rubin, RedState editor Erick Erickson, MSNBC host Joe Scarborough, and Iowa radio personality Steve Deace. Although they held varying opinions of Trump until recently, they agree today that his appeals to bigotry, his despotic attitudes, and his coziness with white supremacists and neo-Nazis are — as Scarborough put it — “disqualifying” for his presidential candidacy.

And while others like Ann Coulter, Mike Huckabee, New Jersey Governor Chris Christie, Senator Jeff Sessions (R-AL), and radio host Hugh Hewitt still promote Trump, to their eternal disgrace, the #NeverTrump conservatives have vowed not to support or vote for him under any circumstances.

Nobody should discount how difficult that stance must be for committed Republicans, especially given the strong likelihood that Hillary Clinton will secure the Democratic nomination. Not a few of them sincerely despise her (and none of them would be thrilled with a President Bernie Sanders, either). Nevertheless they appear to realize that Trump is in a wholly different category from any normal partisan or ideological foe. There is more at stake than a single election, even an election as significant as this one.

It is fair to wonder why so many conservatives didn’t seem to comprehend Trump’s toxic essence from the moment he brayed about Mexican “rapists” in his rambling announcement speech. For too long, right-wing pundits and politicians seemed much more disturbed by his past positions on healthcare, abortion, and guns than his current appeals to racism, xenophobia, and violence. Even last January, when the National Review devoted an entire issue to essays scourging Trump, most contributors worried about his issue positions and electability rather than his demagogic contempt for American values.

Unfortunately, the Republican Party and the conservative movement have not yet confronted the profound problems that Trump did not cause but merely symbolizes. His rise can be traced to the racial undercurrent in the Tea Party movement, the segregationist legacy of Jesse Helms and Strom Thurmond, the Willie Horton tactics used by George H.W. Bush, and the Southern strategy deployed by Richard Nixon – indeed, the whole long history of ugliness not just tolerated but often celebrated on the right. Combined with the coarse, vacuous culture epitomized by Fox News and encouraged by the right’s leading intellectuals, that tainted history made someone like Trump almost inevitable.

Whether the party of Abraham Lincoln can be preserved and rehabilitated in the aftermath of a Trump nomination remains to be seen. For conservatives determined to rescue their movement and their party from fascist perdition, the way forward is clear if painful. Author and journalist Max Boot — who was among the first conservatives to reject Trump for the right reasons — addressed the depth of their dilemma with refreshing candor.

“I’m a lifelong Republican,” he reflected on Twitter the other day, “but [the] Trump surge proves that every bad thing Democrats have ever said about GOP is basically true.” Bitter as it is, that verdict may signal the possibility of real reform someday.