CHICAGO (CBS) — Conservative talk show host and former Republican congressman Joe Walsh announced he will challenge President Donald Trump in the 2020 GOP primary.

On Thursday, Walsh told CNN’s John Berman on “New Day” that he was “strongly considering it.” On ABC’s “This Week” on Sunday, Walsh said he was indeed going to launch a run.

“We’ve got a guy in the White House who’s unfit – completely unfit to be president,” Walsh said Sunday on ABC’s “This Week.” “And it’s stunned me nobody stepped up, nobody in the Republican Party stepped up.”

A former congressman from a northwest suburban Chicago district, Walsh said if he does decide to run against Trump, he would “punch him every single day.”

“Trump’s a bully and he’s a coward, and the only way you beat a bully and you beat a coward is to expose them, is to punch them,” Walsh said. “The only way you primary Donald Trump, and beat him, is to expose him for the conman he is.”

The new presidential candidate has a history is making controversial statements. He said President Barack Obama was a Muslim, hated Israel, and won the presidency because he was – in Walsh’s words then – “a black man who was articulate.”

On Sunday, the apologetic Walsh said that rhetoric led to President Trump.

“I got personal and I got hateful,” Walsh said. “I said some ugly things about President Obama that I regret. And it’s difficult but I think that helped create Trump.”

Walsh has personal baggage too – financial troubles, a foreclosure, and accusations from his ex-wife that he was delinquent in his child support.

He now faces an enormously difficult task in the GOP – taking on a president who has more than 80 percent support among Republicans. But Walsh assesses Trump in no uncertain terms now.

“Somebody needs to call him out, and I can’t believe nobody in our party is calling him out, and I cannot believe nobody in our party is calling him out,” Walsh said.

Last week, Walsh also apologized for his role in helping elect Trump. He said he voted for Trump in 2016, but only because he wasn’t Hillary Clinton. Where Trump lost him, Walsh said, was during his press conference with Vladimir Putin in Helsinki last year in which he sided with the Russian strongman over his own intelligence community’s assessments of interference in the 2016 election.

In a recent op-ed in the New York Times, Walsh accused Trump of being a “racial arsonist who encourages bigotry and xenophobia to rouse his base and advance his electoral prospects.”

Walsh served only one term in Congress, representing the 8th District in the northwest suburbs, losing to Democrat Tammy Duckworth in 2012, but said he’s confident he could beat Trump. He said he thinks any “good challenger” could beat the president in the Republican primary, if they make the case that Trump is unfit to serve in the White House.

There was no response from President Trump Sunday on Walsh’s announcement.

Walsh is President Trump’s second Republican challenger. Former Massachusetts Gov. Bill Weld is also in the race.