Former Rep. Joe Walsh, R-Ill., a national talk show host and former Illinois congressman announced Sunday he will enter the Republican Party primary against President Donald Trump for the presidential nomination.

Walsh announced his candidacy on an ABC television show, on which he said, “We’ve got a guy in the White House who’s unfit, completely unfit to be president.”

This announcement makes him the second person to declare a campaign to secure the Republican Party nomination after former Massachusetts Gov. Bill Weld declared his candidacy in April. Walsh has said that he is responsible for “creating Donald Trump,” and wants to oust the incumbent.

When asked about the 25th Amendment to the Constitution, which has a provision for removing a president, Walsh said, “It should be looked at.”

Walsh said he voted for Trump in 2016, but came to oppose him on several issues, including trade and the economy. He asserted Trump has not been fiscally conservative, is causing damage to the economy and has increased the national debt. During his announcement, Walsh said, “The president of the United States is tweeting us into a recession.”

Mack Shelley, Iowa State professor and chair of the political science department, said trade policy is an area where President Trump could lose support in places like Iowa. Shelley said tariffs imposed by the Trump administration have caused hardships for growers and reduced available markets overseas.

“That doesn’t help Trump one bit in farm country,” Shelley said.

Walsh has accused the president of being a narcissist, a liar and of obstructing justice. On Aug. 19, he tweeted, “There must be a Republican primary referendum on Trump. Not a referendum on tariffs. Not on the debt & deficits. Not on the wall. It’s gotta be a referendum on Trump. A referendum on his unfitness. His dishonesty. His disloyalty. His cruelty. His incompetence. His narcissism.” 

President Trump’s personality has been a focal point for Walsh, but Shelley voiced doubts about whether it is an effective tactic.

When speaking about Republican voters, Shelley said, “I don’t think they care a heck of a lot one way or another from one tweet compared to another.”

Alluding to a phrase describing former President Ronald Reagan, Shelley described Trump as a “teflon” president whose base of support isn’t affected greatly by attacks on his personality.

Shelley said Walsh could secure a portion of libertarian and farther right-leaning conservative voters, as well as some of what is known as “never-Trump” support. Despite the niche that Walsh could find, Shelley said he doesn’t think he will win the Republican nomination because of Trump’s 88-89% approval rating within the party.

Every publicly available opinion poll has found Trump with at least 90% support among likely Iowa caucusgoers.

If Walsh were to win the primary, Shelley expects him to lose and not gain more than 40% of the popular vote. Even though Walsh’s candidacy is not currently a major threat to Trump’s campaign, Shelley said he thinks he could take some Republican voters who aren’t satisfied with the president and cause damage for the general election. 

“I would think Trump has to worry a little bit,” Shelley said.