Former Rep. Joe Walsh (R-Ill.) is reportedly expected to announce his candidacy for president, becoming the second prominent Republican to challenge President Trump Donald John TrumpFederal prosecutor speaks out, says Barr 'has brought shame' on Justice Dept. Former Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick MORE for the party's nomination.

The New York Times reported Wednesday that Walsh, now a radio host, will announce his candidacy as early as the weekend. Walsh argued in an op-ed for the newspaper last week that the president needed a primary challenge from the right and told the Times in an interview that he would announce his intentions before Labor Day.

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Walsh would join former Massachusetts Gov. Bill Weld William (Bill) WeldRalph Gants, chief justice of Massachusetts supreme court, dies at 65 The Hill's Campaign Report: Biden visits Kenosha | Trump's double-voting suggestion draws fire | Facebook clamps down on election ads Biden picks up endorsements from nearly 100 Republicans MORE (R), who announced his candidacy earlier this year, as the second Republican challenger to mount the long-shot challenge against Trump, whose approval rating among Republicans has hovered above 50 percent since he took office in 2017.

The former congressman supported Trump during the 2016 election but has hammered the president for his conduct in the years that followed. Earlier this year, he sharply criticized Trump over behavior outlined in Robert Mueller Robert (Bob) MuellerCNN's Toobin warns McCabe is in 'perilous condition' with emboldened Trump CNN anchor rips Trump over Stone while evoking Clinton-Lynch tarmac meeting The Hill's 12:30 Report: New Hampshire fallout MORE's report that detailed the results of the special counsel investigation into the Trump campaign.

"I don't know how anybody can read this report and think, 'This is behavior that we want in our president,'" he told CNN's Brooke Baldwin at the time.

"Criminal behavior, who knows?" he added. "But, boy, dishonest, immoral, unethical? Heck yes it is. And I’ll tell you, Brooke, every Republican on Capitol Hill agrees with what I just said. They can’t say that publicly."

Walsh previously served one term in Congress as a Tea Party-aligned Republican and swiped at Weld as a centrist earlier this month in the Times op-ed.

“The president is more vulnerable to a challenge from the right. I’m on the right, and I’m hugely disappointed that challenge hasn’t yet materialized,” Walsh wrote at the time.