House Speaker Paul Ryan dropped a bombshell Thursday afternoon by announcing he is not yet willing to support Trump. “I am not there right now,” Ryan told CNN’s Jake Tapper, adding that the presumptive nominee still needs to prove his conservative bona fides and work to bring the party’s disparate wings aboard. “Conservatives want to know, does he share our values and our principles on limited government, the proper role of the executive, adherence to the Constitution? There are lots of questions that conservatives, I think, are going to want answers to, myself included.”

That after 10 months, and no shortage of interviews and widely covered appearances, Trump hasn’t satisfied his party’s highest-ranking elected officer on such basic points speaks volumes about the crisis of leadership facing the GOP right now. And Ryan isn’t alone. The last two Republican presidents — George H.W. Bush and George W. Bush — as well as the last two Republican presidential nominees — Arizona Sen. John McCain and former Massachusetts Gov. Mitt Romney — all plan to skip the GOP’s national convention in July, rather than turn up to lend Trump an image of the party uniting around him.

Romney, the 2012 nominee, has been particularly sharp in his public critique of the presumptive Republican standard-bearer, calling him “a phony, a fraud” who has “neither the temperament nor the judgment to be president” in a March speech. And while McCain, the 2008 nominee, has said he’ll support his party’s candidate, he told donors at a fundraiser last month that the antagonism Trump is stirring among Hispanics in his home state is imperiling his own reelection bid there.

Trump hasn’t come up empty with the entirety of the GOP brass: Ryan’s partner across the Capitol, Senate Majority Leader Mitch McConnell, on Wednesday offered a decidedly unenthusiastic statement of support. “I have committed to supporting the nominee chosen by Republican voters, and Donald Trump, the presumptive nominee, is now on the verge of clinching the nomination,” the Kentucky Republican said in a statement, adding Trump now has “the opportunity and the obligation to unite our party around our goals.”

But Ryan’s jaw-dropping rebuke carries immediate consequences for Trump’s campaign. It potentially freezes two key camps that the gatecrashing nominee needs to recruit to his cause: down-ballot Republicans and the donor class. In his CNN interview, Ryan explicitly pointed to the imperative of preserving the House Republican majority, the party’s biggest in that chamber since 1928. Some political handicappers believe Trump’s candidacy could prove toxic enough to put that control at risk, and House Republicans facing competitive races have been slow to endorse him. Ryan’s move offers cover to those in his ranks anxious for more time before announcing themselves.

Perhaps of more immediate concern to Trump, the stiff-arm from Ryan signals to deep-pocketed conservative moneymen that they can continue hugging the sidelines. It’s not yet clear how Trump plans to finance his general election bid — and what role he intends to carve out, if any, for donors who can cut massive checks, say, to a super PAC supporting his run. But as long as Republican leaders remain in such open disarray, it could prove difficult for Trump to forge inroads with traditional GOP funders.