Former Republican Rep. Joe Walsh is calling for a primary challenger to take on President Donald Trump in 2020, as he is reckoning with his past controversial comments and apologizing for his role in helping elect an "unfit con man" to the presidency.

"If Republicans don't stand up right now and challenge this guy right now, he's bad for the party. He's bad for the country. We're going to get wiped out in 2020," Walsh said Thursday in an interview on CNN's "New Day," echoing his recent op-ed in the New York Times.

In his Times op-ed published Wednesday, Walsh argues that Trump -- who enjoys high approval ratings among Republicans -- is "more vulnerable to a challenge from the right" rather than a centrist challenge, pointing to former Massachusetts Gov. Bill Weld's GOP candidacy.

Walsh told CNN's John Berman on Thursday that he knows "a lot of good people are thinking about primarying Trump," without naming names.

"It's got to be the moral case. This has got to be a mission. This guy is unfit to be President," Walsh said.

He argued that what Republicans need is "somebody to stick their neck out and say, 'Enough. Enough, President Trump. We're tired of the lies. We're tired of the bullying. We're tired of the cruelty. Enough.' Somebody has to break that impasse."

In his op-ed, Walsh accuses Trump of being a "racial arsonist who encourages bigotry and xenophobia to rouse his base and advance his electoral prospects."

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