UPDATE 1-Joe Walsh becomes second Republican to challenge Trump for White House

Joe Walsh, a conservative former U.S. congressman turned talk show host, on Sunday became the second Republican to challenge President Donald Trump for the party's 2020 White House nomination.

Walsh criticized Trump, who has strong support among Republicans, as a bully who is unfit for office as he announced his long-shot bid. "I'm running because he's unfit," Walsh, 57, told ABC's "This Week" program. "Somebody needs to step up."

"He's a bully and he's a coward and somebody needs to call him out," Walsh said. "The best ... of my campaign is that there are a lot of Republicans that feel like I do. They're afraid to come forward." Walsh won a House of Representatives seat from Illinois as a candidate of the Republican Party's fiscally conservative Tea Party movement in 2010 but was defeated by Democrat Tammy Duckworth in his 2012 re-election bid. After leaving Congress, he became a Chicago-area radio talk show host.

William Weld, a former Massachusetts governor, had been the only Republican trying to unseat Trump, but his candidacy has so far failed to gain traction. Former U.S. Representative and South Carolina Governor Mark Sanford said in July he was considering a primary challenge because of the rising federal debt.

Any Republican challenger will face a formidable re-election effort mounted by Trump, who has consolidated his grip on the party's national and state machinery. A Reuters/Ipsos poll conducted Aug. 19-20 showed 87% of Republicans approve of his performance in office. Walsh said he was undeterred. "I think this thing ... will catch on like wildfire," he said.

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