WASHINGTON – President Trump should have a conservative challenger in 2020 who believes in free trade, limited government and economic freedom, said outgoing Republican Sen. Jeff Flake.

“I do,” Flake of Arizona responded Sunday when asked if Trump needs an opponent from the right.

“It would be a tough go in a Republican primary. The Republican Party is the Trump party right now. But that’s not to say it will stay that way, ” he said.

Flake, a frequent Trump critic, is retiring from the Senate because he said his traditional conservative views and temperament aren’t accepted in the age of Trump.

“I couldn’t be reelected in my party right now,” Flake told NBC’s “Meet the Press.”

Trump has already announced his 2020 slogan – “Keep America Great!” – in a wide-ranging speech in Saturday in Pennsylvania where he also bashed the media, touted new tariffs on steel and aluminum imports and suggested imposing the death penalty on drug dealers.

“We should never normalize this kind of behavior, particularly from the president of the United States,” Flake said. “So I think it does real damage long term to the political culture. It really does.”

Flake this week is traveling to New Hampshire, the first presidential primary state, which stoked speculation of a possible presidential bid against Trump.

Ohio Gov. John Kasich has also kept the door open to another presidential bid.

“All options are on the table,” Kasich told CNN last week, “both for me in my private, my professional life. But I want to keep a voice, because I think it’s important, whether it’s trade, immigration.”