It's way too early to think about the 2020 presidential primaries — too early for normal people, that is. But that hasn't stopped politicians in both parties from doing just that. And yes, that includes Republicans, many of whom are already pondering who might challenge President Trump for the GOP nomination three years from now.
"I don't see how we can avoid it," Vin Weber, a former Republican congressman, told me recently. "It's pretty clear someone's going to do it."
"I think he's inviting one," Sen. Jeff Flake of Arizona, one of Trump's GOP critics, said last month.
"There should and will be a challenge," agreed William Kristol, editor at large of the conservative Weekly Standard. Kristol, another Trump scourge, has launched a project he jokingly calls the Committee Not to Renominate the President.
Like so much else about the Trump presidency, this is unusual.
Presidents have faced challenges within their parties before, of course. It's happened four times since 1968, when Eugene McCarthy ran against Lyndon B. Johnson. But it's unusual for intra-party feuding to begin this early, eight months into a newly elected president's first term.
In Trump's case, the causes are easy to find.
The GOP is deeply divided, and the president hasn't done much to heal the breach. Quite the contrary. He has attacked his party's leaders in Congress. He has strayed repeatedly from GOP orthodoxy, most recently when he made a quick deal over the debt ceiling with Democrats Charles E. Schumer and Nancy Pelosi. He still tweets about Republicans as if he weren't one of them — which, until recently, he wasn't.
If Trump's 2016 campaign was a hostile takeover, it's a takeover that remains incomplete, especially in the party's political class. And by continuing to run against the establishment, Trump is increasing the chances that one of its members will run against him.
Besides, the president is unpopular. His approval rating in the Gallup poll has settled at a dismal 37%. That puts him in the zone of electoral vulnerability that drew challenges to Presidents Ford in 1976, Carter in 1980 and George H.W. Bush in 1992.
One more factor: the slim possibility that Trump might not run again, whether because of the investigation into his campaign's ties to Russia or, less likely, because he's tired of the job. That's been enough to persuade some potential candidates to visit Iowa and New Hampshire, just in case.
Who might run?
At the very least, there's likely to be a conscience candidate, a Never Trumper who can't abide the thought of the president sailing to renomination without a fight. Sen. Ben Sasse of Nebraska might fit that bill.
There's a still-vocal runner-up from 2016: Ohio Gov. John Kasich. He says he won't run as a third-party independent, but he won't rule out entering the Republican race.
There could be a grudge candidate, someone savaged by Trump who might enjoy afflicting him in return. That could describe Flake or Sen. Lindsey Graham of South Carolina.
And, circling nearby, there's a long list of more conventional candidates ready to swoop in if the incumbent falters: Sens. Ted Cruz, Marco Rubio and Tom Cotton — even, if the president should drop out, Vice President Mike Pence.
Trump's campaign organization, which never stopped for a rest after last year's election, appears to take all this seriously. The president has already held rallies and fundraising events in swing states; that's unusual, too.
Last month, his campaign pollster, Tony Fabrizio, released survey results designed to show, in his words, Trump "crushing a hypothetical GOP field." Actually, it showed the president winning a not-very-intimidating 50% of Republican votes, including 54% of Republicans who said they would definitely show up for the primaries. Cruz was in second place, with 14%; Kasich was third, with 10%.
Despite that less-than-impressive 50%, however, Fabrizio was right that Trump is likely to defeat any combination of rivals.
The history of recent primary challenges is remarkably consistent: The incumbent wins the nomination. That's what happened when Ronald Reagan challenged Ford in 1976, when Edward M. Kennedy challenged Carter in 1980, and when Patrick Buchanan challenged Bush in 1992.
That doesn't mean a primary challenge has no consequences. In each of those three campaigns, the primary battle divided the party, sapped the incumbent's popularity — and helped the other party's nominee win the general election in November. The most likely effect of a primary challenge, if one happens, is a boost for Trump's eventual Democratic opponent.
But the long odds may not deter potential challengers. We sometimes forget that politicians run for president for many reasons — reasons that often have little to do with the odds of success. Some run because they think they can win. Others run on sheer passion, to promote favorite ideas, to change their party's direction, or because they sense they're running out of time.
"I've got a message," Kasich said last month. "We all get old and we all leave this planet. So we're going to be judged in many ways by what we did when we were here."