“He’s just new to this,” offered Paul Ryan, the speaker of the House, by way of explanation for President Trump’s oafish efforts to get James Comey, then the F.B.I. director, to drop the bureau’s investigation of Michael Flynn, the former national security adviser. Mr. Trump stumbled, Mr. Ryan went on, because he is “learning as he goes,” and because “he wasn’t steeped in the long-running protocols that establish the relationships between D.O.J., F.B.I. and White Houses.”

With these impressive bits of casuistry, Mr. Ryan became the unofficial leader of the Trump Excuses Caucus. This caucus is composed exclusively of Republicans. Some of its members remain staunch supporters of Mr. Trump, while others are doubtless panicked about their political futures with Mr. Trump strutting about at the head of the party, insulting everyone and everything in sight: staff members, allies, laws, diplomatic decorum and common sense.

There was a day when Republicans like Mr. Ryan derided President Barack Obama as inexperienced. If Mr. Obama had fired an F.B.I. director who was leading an investigation of his associates — he didn’t, and there was never any such investigation — can you imagine Mr. Ryan treating the action as a learning experience?

Thin-skinned as he is, Mr. Trump ought to be offended by Mr. Ryan’s condescension. The president obviously knows that it’s wrong to interfere in an investigation. As a candidate, he repeatedly condemned Bill Clinton’s tarmac conversation with Loretta Lynch, then the attorney general overseeing an investigation into Hillary Clinton’s use of a private email server.