Former Illinois Congressman Joe Walsh told ABC News on Sunday that he plans to challenge President Trump in the Republican presidential primary.

"He's nuts. He's erratic. He's cruel. He strokes bigotry. He's incompetent. He doesn't know what he is doing," Walsh said. "We've got a guy in the White House, who is unfit, completely unfit to be president and it stuns me that nobody has stepped up." 

A recent poll showed 78% of Republicans approve of Trump's job performance. But there has long been criticism from the right against Trump, particularly from Republicans who disapprove of his fiscal deficits and trade protectionism. 

When a Trump campaign spokesperson was asked about Walsh's decision to run, they replied "whatever." 

Walsh, 57, was elected to Congress in 2010, as Republicans retook the House on a wave of anti-Obama sentiment. Walsh, who represented Illinois's eight district in the Chicago suburbs, considered himself part of the Tea Party, a conservative movement whose name stands for Taxed Enough Already. 

Many of the so-called Tea Partiers were angry about the passing of the Affordable Care Act, with many of them considering the law's individual mandate a tax that hurts personal freedom.

Walsh consistently voted against raising the debt ceiling during his term and believed that Obama was bankrupting the United States. He lost re-election against Democratic candidate Tammy Duckworth in 2012. 

Although Walsh criticizes Trump for his controversial statements, he has made some of them himself, especially in opposition to former President Barack Obama.

He has said that the Democratic Party seeks to make Latinos dependent on the U.S. government just like "they got African Americans dependent on the government." He has also blamed Obama for police shootings in Dallas in 2016. 

Walsh has made Islamophobic comments similar to Trump, as he has called Obama a Muslim and said that Muslims are trying to take over the Chicago suburbs. 

Walsh said that he regrets some of the comments he has made. 

Walsh isn't the only Republican challenging Trump. Former Massachusetts Gov. Bill Weld is also running in the GOP primary, while former Republican South Carolina Gov. Mark Sanford and former Ohio Gov. John Kasich have not ruled out running.