Conservative firebrand Joe Walsh, a radio host and former Illinois congressman, will challenge President Donald Trump for the Republican nomination in 2020.
In an interview with ABC's George Stephanopoulos, Walsh confirmed that he will challenge Trump, whom he called "unfit to be president" in a scathing critique.
"I'm going to run for president, and I'm happy to be on your show announcing my candidacy," he said. "We've got a guy in the White House who is unfit, completely unfit to be president. And it stuns me that nobody stepped up. Nobody in the Republican Party has stepped up.
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"The country is sick of this guy's tantrums. He's a child," he added.
Walsh had initially floated the idea of challenging Trump in a CNN interview Thursday, and had promised to make up his mind within a week of the sit-down.
Walsh was elected to represent Illinois' 8th Congressional District in the Tea Party wave of 2010 and served one term before he was defeated in the newly-drawn 8th District by now-Sen. Tammy Duckworth.
Initially a Trump supporter, Walsh - who has a history of making controversial comments - tweeted in October 2016, "if Trump loses, I'm grabbing my musket." But he has since soured on Trump, repeatedly calling him "unfit to be president" and "dangerous," among other things.
Now, Walsh has changed course, announcing that he will try to challenge the president on "moral" grounds.
"We've never had a situation like this. You can't believe a word he says. He's nuts, he's erratic, he's cruel, (and) he stokes bigotry," Walsh said.
This is not the first time Walsh has threatened to challenge a GOP incumbent. In October 2017, Walsh tweeted that he was "done" with then-Illinois Gov. Bruce Rauner should Rauner sign legislation to prevent law enforcement from detaining individuals based solely on their immigration status.
After Rauner signed a so-called "sanctuary state" bill, Walsh floated the idea of running against him in the Republican primary or afterwards as an Independent - though he ultimately did neither.
Walsh will likely pose little threat to Trump, whose approval rating among Republicans stands at around 88 percent, according to an August Gallup poll, and who has a roughly $41 million political war chest.