Former Illinois congressman Joe Walsh announced Sunday that he will challenge President Donald Trump in the 2020 primary, becoming the second Republican to wage a bid against the president.

Walsh, a talk-radio host, was elected to Congress in 2010 as part of the tea party wave and served one term. He has described himself as an immigration hard-liner and said he would not challenge Trump from the center but from the right and on moral grounds.

"I'm going to run for president," Walsh said Sunday in an interview on ABC News' "This Week," charging that the president is "incompetent," "a bigot" and "a narcissist."

Former Massachusetts Gov. Bill Weld also has declared that he is running against Trump in the Republican primary, but he has struggled to gain traction.

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Asked about Walsh's entry into the race, Trump campaign spokesman Tim Murtaugh replied, "Whatever."

Weld, meanwhile, welcomed Walsh's arrival, saying he was "thrilled" by the news.

"I think that's terrific," he said on NBC News's "Meet the Press." "And it's going to be a more robust conversation. Who knows? The networks might even cover Republican primary debates."

In Sunday's interview, Walsh staked his run on harsh criticism of the president and questioned Trump's support among Republicans, despite polls showing that the president is popular with the overwhelming majority of GOP voters.

According to a Monmouth University poll released last week, 84% of Republicans approve of Trump's job performance. His highest recent approval mark among fellow Republicans was 88% in a Fox News poll of registered voters earlier this month.

"He's nuts. He's erratic. He's cruel. He stokes bigotry. He's incompetent. He doesn't know what he's doing, George, he's a narcissist," Walsh told host George Stephanopoulos.

Walsh also released an announcement video in which he called on Americans to have "the courage to finally say publicly what we all know privately: We're tired."

"My name is Joe Walsh. I'm a former Republican congressman. I'm a conservative. I'm running because Donald Trump is not who we are. In fact, he's the worst of who we are," Walsh says in the video.

In the "This Week" interview, Walsh apologized for his past criticism of former President Barack Obama during his time in office, saying he and other tea party Republicans helped create a partisan political environment that facilitated Trump's election.

"I got personal and I got hateful. I said some ugly things about President Obama that I regret . . . that helped create Trump, and I feel responsible for that," he said.

But Walsh has also made inflammatory comments in more recent years, and Stephanopoulos raised some of those remarks in the interview, describing them as "textbook racism and sexism."

In March 2017, Walsh tweeted that the country held Obama "to a lower standard cuz he was black." Months later, Walsh made a similar remark about Sen. Kamala Harris, D-Calif., stating, "If you're black & a woman, you can say dumb things. Lowered bar."

Stephanopoulos noted Sunday that Walsh "called President Obama a Muslim, an enemy, a traitor. And you often spoke out on racial themes."

Walsh, who has said he voted for Trump in 2016, responded by claiming that the president's rise had caused him to reconsider his past remarks.

"Well, again, the beauty of what President Trump has done is, George, he's made me reflect on some of the things I have said in the past," he said. "I had strong policy disagreements with Barack Obama, and too often I let those policy disagreements get personal."

Stephanopoulos pressed him: "Did you really believe he's a Muslim?"

"God no," Walsh replied. "And I have apologized for that."

Walsh also faced a child-support dispute with his ex-wife that ended in a settlement in 2012.

Others who are mulling Republican primary challenges against Trump include Mark Sanford, a former South Carolina governor and congressman, and former Ohio Gov. John Kasich.

Jeff Flake, a former senator from Arizona and a Trump antagonist, also has said he has taken a flurry of recruitment calls from GOP donors rattled by signs of an economic slowdown and hungry for an alternative to Trump.

This article was written by Felicia Sonmez and Joe Marks, reporters for The Washington Post.