Updated at 11:45 a.m. ET
Joe Walsh, a conservative talk-radio host and former Tea Party congressman, is launching a long-shot primary challenge to President Trump. He's the second Republican to officially announce a run against Trump, who has a strong approval rating among his party's base.
Walsh, 57, supported Trump during his 2016 campaign but in recent months has been offering a bitter critique of the president, calling Trump a liar and bully who is unfit for office. Walsh has also attacked Trump from the right.