IT WAS an “extraordinary rebuke” of Donald Trump, according to various news reports. Or was it? House Speaker Paul D. Ryan (R-Wis.) said this week that he is “not ready” to endorse the presumptive Republican nominee — “at this point.” But, he added, “I hope to, though, and I want to.” How could Mr. Trump change the speaker’s mind? He must “do more to unify this party to bring all wings of the Republican Party together, and then to go forward and to appeal to all Americans and every walk of life, every background,” Mr. Ryan said.

While not the ringing condemnation Mr. Trump deserves, Mr. Ryan’s statement puts him ahead of many in his party. Some, such as Republican National Committee Chairman Reince Priebus, immediately caved after Mr. Trump won the Indiana primary. Others have tried to have it both ways, supporting Mr. Trump while also distancing themselves from the billionaire. “I have committed to supporting the nominee chosen by Republican voters, and Donald Trump, the presumptive nominee, is now on the verge of clinching that nomination,” Senate Majority Leader Mitch McConnell (Ky.) said.

Sen. John McCain (R-Ariz.) and others have also adopted this rhetorical strategy, even as they have registered varying levels of discomfort with Mr. Trump’s proposals. Their moral error is blatant: Endorsing an unprincipled and unprepared man to run the country is more dishonorable than breaking a partisan commitment. Republicans cannot evade responsibility by attempting to distinguish between supporting the “Republican nominee” and endorsing Mr. Trump. Even tepid endorsements count.

Other Republicans have found the backbone to say what they know — or should know — to be true: that Mr. Trump has not “displayed the judgment and temperament to serve as commander in chief.” Those are South Carolina Sen. Lindsey O. Graham’s words, explaining why he will support neither Mr. Trump nor Hillary Clinton in November. Former Massachusetts governor Mitt Romney has taken a similar stand. Sen. Dean Heller (R-Nev.) has not fully repudiated Mr. Trump, but he indicated he might vote for “none of these candidates,” an option on the Nevada ballot, in the general election. Jeb Bush said Friday he would not vote for Mr. Trump. Spokespeople for both Presidents Bush said that they would not be commenting on the election, though each has endorsed GOP nominees in past elections.

The morality of the situation demands more than Mr. Ryan’s “we’ll see.” Yet the speaker has set standards for himself, and we expect that he will live by them. When Mr. Ryan says that Mr. Trump must “appeal to all Americans,” we wonder how this could ever be accomplished by a man who has mocked the disabled, attacked women in appalling terms, belittled Jews, Latinos and others, proposed banning Muslims from entering the United States and threatened political opponents, the free press and the speaker himself. According to Mr. Ryan’s words, swearing fealty to the GOP ideological agenda — tax cuts, smaller government, states’ rights and so forth — would not be enough. Mr. Trump would have to be a different person and have run a different campaign.

Mr. Ryan and Mr. Trump are set to meet next week, and Mr. Priebus wants them to patch things up. But if the speaker really meant what he said, the only way he could support Mr. Trump is if the billionaire withdrew from the race.