Former Illinois Representative Joe Walsh on Sunday announced that he would challenge President Donald Trump for the Republican presidential nomination.

Walsh, a former vocal supporter of Trump during the 2016 election cycle, said that Trump was unfit for the office and should be denied a second term.

During an appearance on ABC's This Week, Walsh – who has a history of using racist slurs and has promoted the “birther” conspiracy during former President Barack Obama's tenure – told George Stephanopoulos that he regretted his past comments.

“We have a guy in the White House who’s never apologized for anything he’s done or said. I think it’s a weakness not to apologize," Walsh told Stephanopoulos. "I helped create Trump, there’s no doubt about that. The personal, ugly politics, I regret that and I’m sorry for that. And now we’ve got a guy in the White House, George, that’s all he does.”

Walsh, however, did not address his vocal opposition to LGBT rights, including marriage equality.

“I'm a strong supporter of traditional marriage and believe that a marriage can only exist between one man and one woman,” he pledged during his 2010 campaign.

In a 2015 tweet, Walsh wrote: “I told Thomas Jefferson that the government was forcing a grandmother to arrange flowers for a gay wedding. He said, 'Grab your Musket!!!'”

In that same year, he said that he carried his gun everywhere, pointing out that “if a bakery can't say no to your gay wedding it can't say no to my gun.”

In a tweet last year promoting a CNN story about a transgender man, Walsh insisted that “a transgender 'man' is a woman.”

During his time in office, Walsh, also a conservative talk radio host, scored zero on the Human Rights Campaign's (HRC) Congressional Scorecard, a measure of a lawmaker's support for LGBT rights.