Dominion Voting Systems threatens to sue Mike Lindell, MyPillow C.E.O., over false claims.

Officials with Dominion Voting Systems have sent Mike Lindell, the C.E.O. of MyPillow, a legal letter warning of pending litigation over his baseless claims of widespread fraud involving their machines.

“You have positioned yourself as a prominent leader of the ongoing misinformation campaign,” the letter said, referring to his continued false claims that their systems were rigged by someone to effect the outcome.

“Litigation regarding these issues is imminent,” the letter said. Mr. Lindell is only the latest to get a warning letter from Dominion officials about potential litigation, after he and Sidney Powell, the right-wing lawyer, Rudolph W. Giuliani and others have continued to spread false claims about the integrity of the results the machines showed.

Mr. Lindell visited Mr. Trump at the White House briefly on Friday, before the national security adviser, Robert C. O’Brien, and the White House counsel, Pat A. Cipollone, steered him away.

In a brief telephone interview, Mr. Lindell said he welcomed a lawsuit from Dominion.

“I would really welcome them to sue me because I have all the evidence against them,” he said. “They sent this letter a couple of weeks ago. They’re lying, they’re nervous because I have all the evidence on them.”