We can’t disagree with any of this, although we’re puzzled by the sense of surprise. Mr. Trump’s debasement of Mr. Sessions — starting with a mind-boggling interview he gave last week to The Times — is in line with everything he’s said and done since he fired James Comey, the F.B.I. director, in May, in an inept attempt to shut down the bureau’s investigation into whether the Trump campaign colluded with the Kremlin to influence the outcome of the 2016 election. Mr. Trump has been unpredictable in many things, but he has been utterly consistent when it comes to resisting any inquiry, however warranted and public-spirited, into his campaign or his close associates.

Mr. Trump’s gratuitous, schoolyard abuse of Mr. Sessions is nonetheless breathtaking. With his thumb-tapping bravado, the president is publicly going after the nation’s top law enforcement officer for doing what professional ethics and department rules required the attorney general to do — recuse himself from any investigations related to the presidential campaign. (Mr. Trump kept up the fusillade on Wednesday, criticizing Mr. Sessions for not firing the acting F.B.I. director, Andrew McCabe, whose wife has political ties to Hillary Clinton.)

Mr. Sessions’s recusal was necessary, of course, because of his role as one of Mr. Trump’s earliest and staunchest supporters, and his own undisclosed contacts with Russian officials — facts that make it impossible for him to maintain the neutrality and independence essential to any credible inquiry. Mr. Trump, who appears to understand little and care even less about the importance of these limitations, thinks Mr. Sessions’s job is to protect him by impeding those investigations. In other words, he expects the attorney general to obstruct justice on his behalf.

Mr. Trump is startlingly blunt about this, calling Mr. Sessions’s recusal “unfair to the president,” as though he is owed a personal loyalty that supersedes the rule of law. The irony is that Mr. Sessions has been the most loyal of Mr. Trump’s supporters, arguably more invested in implementing the Trump agenda than the president himself.

This page is no fan of Mr. Sessions, whose dark vision of America includes a hard-line stance on illegal immigration, a return to the war on drugs and other discredited tough-on-crime policies, and a government newly empowered to seize cash and other property from ordinary citizens without due process. But just as Mr. Sessions was right to recuse himself, he is right to stand his ground now, effectively daring Mr. Trump to fire him.