Paul Ryan is trying to turn Donald Trump into a Republican.

The speaker of the House today told Jake Tapper that he would not support Trump in a general election—at least not yet. “I hope to support our nominee,” he said. “I’m just not there right now.” The conditions for his support? That Trump begin to unify the Republican Party by advancing its principles and becoming a “standard-bearer that bears our standards.”

There is a fair amount to unpack here, in what amounts to a pretty extraordinary development: a sitting speaker refusing to endorse his party’s nominee for president. On one level, it gives the members of his caucus leeway to support or reject Trump as they see fit. On another, it puts distance between the GOP and Trump’s more hateful remarks, which Ryan has condemned in the past. Today, he said the GOP’s presidential candidate must appeal “to a wide, vast majority of Americans.”

But on yet another level, it can be read as a warning to Trump that if he strays too far from Republican orthodoxy in the general election he can expect no love from the party. Ryan is the author of the so-called principles that are embedded in the GOP’s soul. They amount to a historic rolling-back of the welfare state, and a massive redistribution of wealth up the income ladder.

That Trump is patently uninterested in entitlement reform, that he rails against the corruption engendered by monied interests, that he has become the race’s most vocal opponent of the kinds of trade deals that corporations love—all of this has helped him win the Republican primary. It is precisely because he doesn’t care for Republican principles that he is so popular among Republican voters. And emphasizing his unorthodox positions is seen as his only feasible path to winning the general.

Ryan’s attempt at a negotiation can thus be read two ways: as a testament to the GOP’s commitment to tolerance, or as a last-ditch effort to preserve a policy platform that Trump has done so much to discredit.