Flake, an outspoken critic of Trump who is not running for reelection to the Senate, told CNN’s David Axelrod in an interview that while he is not “planning” to run as an independent, he “wouldn’t swear it off.”

“I do think the president will have a challenge from the Republican Party, I think there should be,” Flake said. “I also think that there will be an independent challenge, particularly if the Democrats insist on putting somebody up from the far left of the party.”