Dominick Reuter / Reuters

Updated on July 9, 2015 at 1:50 p.m.

It was fun while it lasted, but Republicans aren’t laughing at Donald Trump anymore. Donors are alarmed and talking about how to bar him from debates. Other GOP presidential candidates are attacking him openly. Even Reince Priebus, the chair of the Republican National Committee, called Trump Wednesday.

But the way that call went down shows just how difficult a challenge it is to keep a lid on Trump. The Washington Post reported on the call Thursday morning, saying Priebus “spent nearly an hour Wednesday on the phone with Donald Trump, urging the presidential candidate to tone down his inflammatory comments about immigration that have infuriated a key election constituency.” Priebus relayed the details of that call to GOP consultants and donors, apparently to calm their nerves.

Then Trump offered his own account of the call. It was a little different:

Donald J. Trump insisted on Thursday that his phone call with Reince Priebus, the chairman of the Republican National Committee, was brief and described it as “congratulatory” instead of condemnatory, in contrast to news accounts of the talk.

“This is shocking,” [said] Mr. Trump, the real estate mogul who is now running for president as a Republican, of descriptions of his conversation with Mr. Priebus on Wednesday that portrayed it as lasting nearly an hour.

Just for good measure, Trump tossed in that Priebus “knew better than to lecture” him.

Clearly, Trump isn’t planning to slink quietly away. And in fact, receiving a call like this from Reince Priebus is exactly what he wants, since it places him front and center and seems to legitimate his place in the Republican firmament. The problem facing Priebus and Co. is that none of the standard tricks a party might have to sideline a candidate are likely to work on Trump.

There are several important caveats here. First, as Mike Allen wryly noted, Republican edginess about Trump isn’t new—though it does seem to be reaching a new pitch. Second, Donald Trump will never be president, for reasons Harry Enten explains at FiveThirtyEight. Third, not all conservative movers and shakers are nervous; Bill Kristol is out there saying his presence is good for the field. Fourth, there’s reason to think that Trump’s numbers will only slide from here.

For the time being, however, he’s easily within the top-10 cutoff for the first GOP debate in August, and he’s even leading in North Carolina in one poll.

How does a party tie down a loose cannon? One method is money. But Trump—even if his own estimates of his wealth are wildly inflated—doesn’t need to worry about donors. His millions allow him to self-fund his campaign, and so he can’t be pressured by big donors.

Moreover, Trump isn’t really a Republican in any meaningful way. Sure, he’s registered as one, and some of his opinions overlap with much of the Republican base. But others don’t. He’s been, at various times, a Democrat and an independent, he’s given to Democratic candidates including Hillary Clinton, and he’s even said he’s pro-choice and favors universal healthcare. (A true cynic might suggest that Trump is politically incoherent and is just running for office for the attention.) Traditional politicians are beholden to a party apparatus and to mentors and friends and colleagues in their party, but with no such ties, Trump is immune to those pressures.

Republicans could also try to keep him off the debate stage, as donor John Jordan proposed, but it’s hard to see what mechanism they might employ. When Fox and CNN set up their debates, with the party’s blessing, they instituted new rules: only 10 candidates, determined by who was polling near the top nationally. In theory, those rules were intended to keep the debates to a manageable size, block out oddball and vanity candidates, and make sure that the Republican Party writ large—rather than just voters in Iowa or New Hampshire, or some subjective and easily criticized group of experts—had a say. In practice, they seem to have cleared the way for Trump’s participation, while threatening to keep out more-established candidates, like Ohio Governor John Kasich, who aren’t polling as well. One potential hangup is that candidates for the Fox News debate are required to have filed financial disclosures. Trump says he’ll do so, but many journalists (this one included) have been skeptical that Trump will be willingly to publicly reveal his true net worth, a subject of frequent debate and litigation.

The biggest problem, however, is media—and specifically, what’s known as “earned media,” publicity garnered in the media without paying. If there’s one thing Trump is good at it, it’s earning media. Think about it this way: Running for president today is a lot like being a reality-TV star. You’ve got to give people the impression that you’re spilling intimate thoughts, always be ready with a buzzy quote, and put yourself in front of a camera as often as possible. Trump has a huge jump on the rest of the presidential field because he already is a reality-TV star.

In the 2012 cycle, Herman Cain got a lot of attention for a short period of time, and briefly led polls. His campaign ultimately fell apart because of the discovery of old sexual-harassment claims and infidelities. Once it became clear Cain was on his way out, the press turned away and he quickly disappeared. Trump’s media arc is unlikely to go the same way. Everyone already knows about his outrageous personality, and he’s famous outside of politics. Plus, he’s willing to talk to reporters all the time. As Dylan Byers reports, the media (and especially TV) love Trump. Trump gave yet another wild, freewheeling interview to the Post Thursday, after making news with NBC on Wednesday. The result is that the Republican Party can’t just sit back and wait for Trump to burn out.

The best news for Priebus is that the very volatility that’s made Trump a star could be his undoing, too. His run has already been very bad for his business empire, and maybe he’ll stop. Or perhaps he’ll say something so outrageous that it finishes him—though at this point it’s tough to imagine what that would be, given that his comments about Mexicans and his resuscitation of birtherism haven’t yet derailed his candidacy. Meanwhile, a campaign that looks like a joke has the potential to materially affect the policy debate in the GOP primary. Priebus has to hope he can find some creative way to fire this celebrity apprentice-politician sooner rather than later.

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