The Anti-Defamation League calls for Tucker Carlson to be fired over ‘replacement theory’ remarks.

The Anti-Defamation League called on the Fox News host Tucker Carlson to resign in an open letter published on Friday, accusing him of giving “an impassioned defense of the white supremacist ‘great replacement theory.’”

Mr. Carlson, in an appearance on Fox News on Thursday, referred scornfully to the term “white replacement theory,” which describes a racist conspiracy theory popular in far-right circles, while arguing that the Democratic Party was “trying to replace the current electorate, the voters now casting ballots, with new people, more obedient voters, from the third world.” He added that naturalized citizens were “diluting” the political power of him and other Americans.

“Everyone wants to make a racial issue out of it, ‘Ooh, the white replacement theory.’” Mr. Carlson went on. “No, no, no, this is a voting rights question. I have less political power because they are importing a brand-new electorate. Why should I sit back and take that? The power that I have as an American, guaranteed at birth, is one man, one vote. And they are diluting it.”

The A.D.L. letter, signed by Jonathan A. Greenblatt, the Jewish advocacy group’s chief executive, said that the language by Mr. Carlson “was not just a dog whistle to racists — it was a bullhorn.”

“This is not legitimate political discourse,” read the letter, addressed to Suzanne Scott, the chief executive of Fox News. “It is dangerous race-baiting, extreme rhetoric And yet, unfortunately, it is the culmination of a pattern of increasingly divisive rhetoric used by Carlson over the past few years.”

Asked on Friday, a representative for Fox News declined to comment beyond highlighting Mr. Carlson’s remarks that said the matter was a voting rights question.

Mr. Carlson has previously claimed that white supremacy is a “hoax,” and prominent companies distanced themselves from his show last summer after comments he made about Black Lives Matter protests.

“This may be a lot of things, this moment we are living through,” Mr. Carlson said at the time. “But it is definitely not about Black lives, and remember that when they come for you. And at this rate, they will.

The “replacement theory” is predicated on the notion that white women are not having enough children and that falling birthrates will lead to white people around the world being replaced by nonwhite people.

An analysis published this week found links between the theory and those arrested in connection with the storming of the Capitol on Jan. 6.

“You see a common pattern in the Capitol insurrectionists,” said Robert Pape, a professor of political science at the University of Chicago. “They are mainly middle-class to upper-middle-class whites who are worried that, as social changes occur around them, they will see a decline in their status in the future.”