IN THE days since he tweeted that four Democratic congresswomen should “go back” to the “broken and crime infested” countries they came from, President Trump has not apologized. Instead, he has shifted the terms of his slander — and in the process gained the support of many Republicans who dared not echo his original racist assault.

The women of color in question, Mr. Trump now maintains, “HATE our Country.” Sen. Lindsey O. Graham (R-S.C.) had the idea: While conceding, unlike Mr. Trump, that the women “are American citizens” who “won an election,” Mr. Graham charged that they “are a bunch of communists. They hate Israel. They hate our own country.” Sen. John Neely Kennedy (R-La.) said, “In America, if you hate our country, you are free to leave.” Sen. Steve Daines (R-Mont.) tweeted that he stood with Mr. Trump because “Montanans are sick and tired of listening to anti-American, anti-Semite, radical Democrats trash our country and our ideals.”

These charges are nominally founded on some of the outspoken statements for which this quartet of Democratic House members — Reps. Alexandria Ocasio-Cortez (N.Y.), Ilhan Omar (Minn.), Ayanna Pressley (Mass.) and Rashida Tlaib (Mich.) — has become famous, including one in which Ms. Ocasio-Cortez characterized migrant detention facilities as “concentration camps.” This is not evidence that she or the others hate the United States, just that they strongly dislike some government policies. It is, by the way, almost surreal to hear Republicans call fellow members of Congress communists — without evidence — after Mr. Trump has spent months cozying up to a real-life Stalinist, North Korean dictator Kim Jong Un.

The right to disagree with the government in strong, even hyperbolic terms is one of the most cherished of American values. As congressional Republicans who savagely attacked President Barack Obama for eight years should recognize, conflating lack of admiration for one particular president, his administration, his policies or his party with disrespect for the United States itself violates the nation’s founding principles. Loyalty to the country does not demand taking an uncritical eye to its history or its present; all it requires is a commitment to the nation’s well-being. Though we disagree strongly with some of the statements and policies these congresswomen have advanced, we do not question their essential allegiance; we welcome the debate they foster.

There was only one acceptable reaction to Mr. Trump’s tweets: condemnation, with no “but” attached to it. The president presumed that the four congresswomen are immigrants, when only one — Ms. Omar — is a naturalized citizen. What, beyond skin color and the sound of their names, could have led him to think otherwise? Mr. Trump’s insistence that they should go back to the “broken” countries they came from rests on the notion that one’s place of origin, rather than the content of one’s character, is a basis for judging the legitimacy of one’s participation in national affairs. And the slander that they “hate” their country is no more tolerable.

The Republican attempt to yoke the whole Democratic Party to these outspoken left-wingers is dishonest but not all that far outside the normal rough and tumble of politics. What is new and frightening is the Republicans’ cynical, almost casual willingness to engage in the basest of slanders about them. Their campaign teaches us nothing about the four women but a great deal about their attackers.

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