Sen. Jeff Flake (R-Ariz.) says the Republican president in the White House is not displaying the conservatism his party should be embracing. In his new book, "Conscience of a Conservative," Flake says populism and protectionism are as threatening to the GOP now as the New Deal was in 1960. (Dalton Bennett,Kate Woodsome/The Washington Post)

Sen. Jeff Flake (R-Ariz.) says the Republican president in the White House is not displaying the conservatism his party should be embracing. In his new book, "Conscience of a Conservative," Flake says populism and protectionism are as threatening to the GOP now as the New Deal was in 1960. (Dalton Bennett,Kate Woodsome/The Washington Post)

We know that President Trump is a virtuoso at the politics of resentment. But does he lead a movement?

That is the question to be tested in next year’s Republican Senate primary in Arizona. Pro-Trump forces are wiping the drool off their ties while contemplating a humiliating primary defeat for Trump critic Jeff Flake — the Republican incumbent whom Trump reportedly calls “the flake.” (I suspect that Flake has heard that taunt before, but not since third-grade recess.) Professional Trump sycophants Sean Hannity and Laura Ingraham have endorsed a Republican challenger to Flake named Kelli Ward. Trump moneyman Robert Mercer has already donated $300,000 to Ward’s campaign. And Trump himself implicitly endorsed Ward on Twitter last month, while labeling Flake as “toxic.”

Recent polling seems to justify a belief in Flake’s vulnerability. Among likely Republican voters, Ward wins a head-to-head with Flake by double digits.

All this would be deeply disturbing for establishment Republicans — if it were not mostly rubbish.

President Trump issued scathing attacks against Arizona's senators during his Phoenix rally on Aug. 22, but said, "I will not mention any names. Very presidential." (The Washington Post)

Polling a year away from a primary has as much predictive power as a tarot pack. The most important factors determining the outcome are entirely contingent. A year hence, Trump could be a vengeful political colossus or headed toward impeachment; the United States could be at war or at peace; the economy could be in depression or riding a boom.

So far, Flake has reason to be pleased with outside interventions in the race. Trump forces in Arizona have not yet settled on Ward — highly inexperienced and gaffe-prone — as their candidate. (“She is not a buffoon,” one close observer of Arizona politics told me, “but she says buffoonish things.”) Outside endorsements of Ward have come as state Treasurer Jeff DeWit and former party chair Robert Graham are discussing which of them might enter the race as a Ward alternative. And Trump himself has since backed off his apparent endorsement of Ward. When Trump visited Phoenix a few weeks ago, he had a backstage meeting with DeWit and Graham. Ward was not invited.

Graham would probably be a stronger candidate than DeWit, who has even less political experience than Ward. Graham gained Trump’s confidence by defending him during the “Access Hollywood” scandal. (True-blue, bona fide Trump loyalists are apparently defined by their willingness to ignore boasting about sexual assault.) But for a Trump challenge to Flake to run smoothly, Graham or DeWit would need to persuade the independent-minded Ward to leave the race. (Recently pardoned octogenarian Joe Arpaio — who lost his last election decisively — likes to talk about running but is not a serious possibility.)

Even if Arizona Trumpites settle on a single candidate, it is not clear what support from “Trump forces” really means. Does a Trump endorsement bring buckets of money? Does it bring organizational help? Trump organizers were thin on the ground even during his own campaign. And the power of presidential tweets to help people other than Trump is untested. Can Trump follow through on his political threats without the normal architecture of a political movement?

The answer depends on a different question, posed to me by the much-respected Arizona Republic political columnist Robert Robb: “Is Trump a singularity, or does he represent the beginning of the redefining of the Republican Party along Trump lines?” Robb, who walked me through the Arizona political basics, is skeptical of the latter. He is doubtful that tea party activists — who rose in reaction (in part) to President Barack Obama’s stimulus package — will be enthused about Trump’s trillion-dollar stimulus package. He is doubtful that Arizona’s generally libertarian and tea-party primary voters will be generally attracted to Trump’s ethno-nationalism.

But who knows? The Flake primary race will be a good test, one way or the other. Flake has been a tough and consistent critic of Trump, based less on ideology than on the president’s preference for vitriolic, tribal politics. But Flake is no moderate. He once ran an Arizona think tank dedicated to conservative and libertarian ideas. He supports Trump on regulatory policy and other issues. To defeat Flake, Arizona voters would need to choose a right-wing populist in the tradition of Pat Buchanan over a libertarian in the tradition of Barry Goldwater. This would involve, not just an electoral choice, but a rethinking of Republican orthodoxy, with far-reaching implications.

If Republicans such as Flake are ousted in primaries, the Republican Party as we know it will be unrecognizable and unsupportable.

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