Former Illinois Rep. Joe Walsh announces he will challenge Trump in Republican primary

Former Illinois Rep. Joe Walsh announced on Sunday that he will run against Donald Trump in the Republican primary for president.

The conservative talk show host said on ABC's "This Week with George Stephanopoulos" that he's running because Trump is "unfit" and "somebody needs to step up."

His announcement comes after an op-ed in The New York Times in which Walsh said a Republican should challenge Trump “from the right.” He said Trump “can’t be trusted.”

“The fact is, Mr. Trump is a racial arsonist who encourages bigotry and xenophobia to rouse his base and advance his electoral prospects,” Walsh wrote.

Walsh, who notably was backed by the Tea Party during his run for office, floated the idea of taking on Trump last week, saying he was “strongly, strongly considering it.”

More: Joe Walsh and the other Republicans who may challenge Trump in the 2020 primaries

Walsh has outspokenly opposed Trump, and he has criticized Trump's relationship with Russia. More recently, he denounced Trump after he tweeted that Democratic congresswomen of color should "go back" to their countries of origin, which prompted chants of "send her back" at a Trump rally.

Calling Trump “a child,” Walsh said Sunday that the country is sick of Trump's lying.

“Look at what’s happened this week. The president of the United States is tweeting us into a recession," Walsh said.

Walsh claimed that most of his Republican colleagues privately agree with his opinions of Trump but are too afraid to speak out against him.

“And it stuns me that nobody stepped up, nobody in the Republican Party stepped up, because I’ll tell you what, George, everybody believes, in the Republican Party, everybody believes that he’s unfit," Walsh said.

Walsh announced his campaign on Twitter Sunday morning, saying “It won’t be easy, but bravery is never easy.”

ABC News’ Jonathan Carl said on the show that the Trump campaign’s only response thus far to Walsh’s challenge is one word: “Whatever.”

Walsh joins former Massachusetts Gov. Bill Weld, who Walsh wrote is challenging Trump “from the center,” in the primary against Trump.

More: Former South Carolina governor says Trump doesn't deserve re-election, is considering GOP primary challenge

This article originally appeared on USA TODAY: Joe Walsh launches 2020 primary challenge against Donald Trump