On Monday, the Republican-led Senate didn't just hand a defeat to gun control supporters. It handed a defeat to its own party's presumptive presidential nominee.

Donald Trump supports prohibiting suspected terrorists from buying guns. He even tried to flex some muscle last week to get the National Rifle Association on board. (After all, Trump pointed out, the NRA has endorsed him — and if his treatment of Chris Christie is any indication, he sees endorsement as something like indentured servitude.)

But the NRA didn't budge, and so neither did the GOP. Sen. Dianne Feinstein's (D-CA) amendment, which would have given the government veto power over gun purchases by "suspected terrorists," failed 47-53.

Two Senate Republicans, Kelly Ayotte (R-NH) and Mark Kirk (R-IL), did vote for Feinstein's amendment. Another, Susan Collins (R-ME), is pushing a narrower compromise proposal. But they're hardly touting the fact that their party's presumptive nominee supports a terrorist gun ban as an argument in their favor. If anything, they're open to such a proposal despite Trump's support: Both Ayotte and Collins have criticized Trump and both are still holding out on endorsing him; Kirk has outright unendorsed Trump while calling him temperamentally unfit to control America’s nuclear arsenal.

Admittedly, Ayotte, Collins, and Kirk are wary of a great many things: Ayotte and Kirk are in tough reelection campaigns. (Collins, too, is a swing state senator.) They have every incentive to moderate.

But Trump isn't Ted Cruz — his appeal isn't limited to the hardcore Republican base. Trump dominated the primaries in Ayotte's home state; Collins's state, for its part, elected the Trumpiest governor in America. But both senators appear to be of the opinion that while Trump is right to be heterodox on guns, his personal brand is so toxic that it makes more sense for them not to cite their party's most prominent champion of their position.

The converse is also true: Despite Trump's theory of how endorsements work, none of the senators who've endorsed him were willing to cross party lines on his behalf. Even Sen. Jeff Sessions, Trump's closest ally in Washington, voted against Feinstein's amendment.

Will Trump shape the GOP?

There's every indication Trump overplayed his hand here. He thought that as his party's standard-bearer he'd have more clout than the NRA, and he was wrong.

It's worth thinking about what that means.

Trump's heterodoxy often comes from his gut; when he's speaking from a teleprompter, he sounds much more like a typical Republican than when he's speaking off the cuff. But his unpredictability often distracts from the truth: His instincts tend toward a relatively coherent politics. He is the candidate of the immoderate center: populists who, inter alia, have ambivalent feelings about guns but very strong feelings about terrorists.

Those voters are Trump's base — the "moderates" he was winning over in early GOP primaries months before the party's conservative wing came around. And they represent a potential alternative base for the GOP as a whole, too: the party of globalization's losers.

The question of whether the GOP as it exists right now — a sclerotic lattice of conservative ideology and interest groups — can remake Trump in its image is settled. The answer is no. But that leaves open the opposite possibility: that he might remake the GOP in his.

The typical way that happens is bottom up: for a politician to support down-ballot candidates who agree with him in intraparty disputes. Donald Trump, who currently has less cash on hand than a competitive Senate race, is clearly not going to do that.

But he could simply lead by example, persuading elected officials and party strategists that he's figured out a winning strategy for the party and inspiring them to reach out to their voters and build their own versions of his coalition. This option still looks open. But Monday's vote is the strongest indication yet that Trump isn't exerting much gravitational pull on his party — that if he loses, the GOP will be able to shake him off with ease.

If you’re worried about the effect of Donald Trump on the American republic, this might sound reassuring. It isn’t, really. The effect Trump has on the Republican Party as an institution is one thing; the effect he has on his supporters — many of whom feel that he has done something brave and necessary in speaking impolitic truths about immigrants in America — is quite another.

If the GOP manages to retain its orthodox (if not calcified) structure after the 2016 election, it simply makes gun control impossible to pass in the long term. If the people Trump has unleashed as a social force adopt some of their leader’s bruised pride and willingness to speak their minds, that will be a problem far beyond the halls of Congress.

How fast 4 different guns can shoot and reload