Republican Sen. Jeff Flake from Arizona is leaving the “door open” for a 2020 run for president and challenge to President Donald Trump.

“I don’t rule anything out, but it’s not in my plans,” Flake said.

“Like I said, I haven’t thought that deeply about it,” he said. “But I do believe if the President is running for re-election, if he continues on the path that he’s on, that that’s going to leave a huge swath of voters looking for something else.”

He also said that Trump is inviting a presidential challenger.

Flake has been an outspoken critic of President Trump, and he recently announced that he will not run for reelection to the U.S. Senate next year.

We’ll see if Flake does initiate a presidential challenge to Trump.