Last weekend, a freshman U.S. representative from Minnesota tweeted a comment that was deemed by many (this editorial board included) to be anti-Semitic and for which she later apologized. In a nutshell, she suggested that Israel has undue influence over the United States because of the money it gives politicians. It’s an old trope, this notion of rich Jewish people controlling the world, and newcomer to Congress or not, Rep. Ilhan Omar should have known better. As a Muslim, her words carried added weight. Even her apology on Monday, while “unequivocal,” was seen as a bit skimpy given her attempt to pivot to a condemnation of money in politics — equating AIPAC (the American Israel Public Affairs Committee which doesn’t actually give money to candidates) with the National Rifle Association (which sure does).

Still, considering the wide condemnation her remarks received from Democrats and Republicans alike, that might have been that. But that was before a certain current occupant of the Oval Office felt an obligation to share his thoughts on the congresswoman, her anti-Semitism and whether she was sincere enough in her apology. That’s right. No less an authority on hate-speech, on insincerity and on how to present oneself as a moral arbiter without knowing the meaning of either word Donald J. Trump decided that the nation was looking to him to provide clarity over what does or does not count as anti-Semitism and remorse.

President Trump as judge of such matters? There is no fact more alternative than that.

Yet there he was on Tuesday talking to reporters prior to a Cabinet meeting, making it clear that not only had Ms. Omar made an anti-Semitic remark but that her apology had been “lame” and she should immediately resign from her office.

We kid you not.

“Anti-Semitism has no place in the United States Congress,” the great man announced. “Congressman Omar is terrible, what she said. And I think she should either resign from Congress or she should certainly resign from the House Foreign Affairs Committee.” He added that he found her apology to be “lame” and suspected that “she didn’t mean a word of it.”

Apparently, “Jews will not replace us,” the chant used by neo-Nazis marching in Charlottesville, Va., in the summer of 2017, was not so anti-Semitic to merit condemnation from a president who instead observed there were “some very fine people on both sides.” Nor was anti-Semitism much on his mind when, a year earlier, then-candidate Trump retweeted an image of Hillary Clinton with a Star of David overlaying hundred-dollar bills with the words, “Most Corrupt Candidate Ever.” Too subtle, perhaps? Or then there were the 2016 campaign ads with images of George Soros, Janet Yellen and Lloyd Blankfein, all Jews, with a warning of “global special interests.” More recently, there was even Mr. Trump’s observation that he “wouldn’t be surprised” if Mr. Soros had provided financing for Central American caravans coming to the southwestern border.

Oh, and let’s not forget the insincerity part. President Trump knows insincerity. At last count, The Washington Post pegged the president at 15 false claims per day in 2018. It’s not clear whether President Trump condemned Rep. Omar because her apology struck him as disingenuous or because she’s such a poseur in this making outrageously false remarks. And if she wants to trade in hate speech? Well, how’s her record on Mexicans (“rapists”) or African-Americans and women (“low-IQ” or “dogs”)? Or how about Muslims (in defending his travel ban, the president recalled watching Arabs in New Jersey cheer the fall of the World Trade Centers; they didn’t). She just can’t be in the same territory.

There’s been a considerable rise in instances of anti-Semitism in this country and many other parts of the world — and, sadly, it goes far beyond rhetoric. The mass shooting at the Tree of Life synagogue in Pittsburgh last October was the worst example of this to date in the United States. Condemning acts of hate should not be so difficult. But it has to start at home. President Trump’s own record is easily as bad as anything Ms. Omar has said, probably worse. That doesn’t make either of them correct. But it does suggest that no political party, left or right, has a lock on anti-Semitism. It’s fair to criticize the Israeli government, but it’s wrong to traffic in stereotypes. Even those who forgive Mr. Trump his daily prevarications need to draw a line here.