Joe Scarborough, the conservative co-host of MSNBC’s political commentary show “Morning Joe,” is leaving the Republican Party.

He made the announcement Tuesday night during an appearance on “The Late Show With Stephen Colbert” alongside his co-host Mika Brzezinski. A two-minute clip of the segment was teased on the program’s Twitter account earlier Tuesday.

Scarborough tore into what he characterized as a complacent Republican Party unwilling to stand up to President Donald Trump.

“You have to ask yourself, what exactly is the Republican Party willing to do?” Scarborough said to Colbert. “How far are they willing to go? How much of this country and our values are they willing to sell out?”

“Aren’t you a Republican?” Colbert asked.

“I am a Republican, but I’m not going to be a Republican anymore,” Scarborough said to loud applause from the audience. “I’ve got to become an independent.”

Scarborough and Brzezinski came under fire from Trump and his administration in recent months for their sharp criticism of his leadership skills and conduct in the White House. The two, who announced their engagement in the spring, once considered Trump a close friend but distanced themselves from the president during his campaign.

They’ve become even more critical after the inauguration in January.

The tension escalated in the last several weeks when Brzezinski called into question Trump’s mental competency in a segment on their show. The president responded in a series of harsh tweets, calling the co-hosts “Psycho Joe” and “low-I.Q. Crazy Mika.” Trump also claimed that Brzezinski “was bleeding badly from a facelift” when he saw her and Scarborough during a brief visit to Mar-a-Lago last year.

In a commentary the hosts wrote and published in The Washington Post, they called the president’s allegations false and offensive and said that they “have noticed a change in his behavior over the past few years.”

“Perhaps that is why we were neither shocked nor insulted by the president’s personal attack,” they wrote. “The Donald Trump we knew before the campaign was a flawed character but one who still seemed capable of keeping his worst instincts in check.”

In the “Late Show” segment, Scarborough and Brzezinski addressed their complicated relationship with the president and his intense dislike of “Morning Joe.”

Colbert asked the duo what specific change they had seen in Trump since he announced his candidacy because, in the “The Late Show” host’s words, the business mogul has always been a “primo tool.”

“He used to know he was a tool,” Brzezinski replied, explaining that they believe Trump used to be aware and in control of the game he was playing. Now, Scarborough said, he is in over his head.

Scarborough said the modern day Republican Party was “not a party that Ronald Reagan could associate with,” and not one he wants to claim any longer either. He told Colbert that he still believes in the core values of conservatism — lower taxes, small government — but that the party’s silence in the face of Trump’s racism is unacceptable.

His dissatisfaction, though, has been building for some time, Scarborough said.

“I think it’s inexplicable. This was well before Donald Trump was elected president that my party has betrayed their core values,” he said, criticizing Trump’s so-called “Muslim ban” and the party’s reluctance to admonish comments perceived as racist, including the president’s assertions that Indiana-born District Court Judge Gonzalo P. Curiel could not be impartial because of his “Mexican heritage.”

“It was disturbing through the entire campaign,” Scarborough said. “In February, when he talked about David Duke and pretended he didn’t know who David Duke was and didn’t know what the Ku Klux Klan did. You didn’t have Republicans coming out, saying ‘I can never support Donald Trump because he’s racist.’ They had 1,000 other excuses why.”

Republicans, he said, turned the other way.

“They’re doing the same thing now and it’s actually disgusting,” Scarborough said, referring to investigations into possible collusion between the Trump campaign and the Russian government.

“What have you heard from Republican leaders today?” Scarborough said. “Nothing. There’s always silence.”

Scarborough has been the conservative voice of “Morning Joe” for a decade, often sparring alongside Brzezinksi. He was a congressman from Florida from 1995 to 2001, and part of a “small group of young Republican congressmen called the ‘New Federalists’ who were said to possess a surprising amount of power given their youth and lack of years in Congress,” according to his MSNBC biography page

That group of hard-line freshman Republicans brought Newt Gingrich to power, though Scarborough told New York Magazine in 2008 that the two “never really clicked.” Scarborough had a “visceral dislike” for President Bill Clinton in the 1990s and supported his impeachment, according to the New York Magazine. He was a staunch fiscal conservative who supported abolishing the Department of Education and cutting off AIDS funding for the Ryan White Act.

During the 2016 election cycle, a Vanity Fair profile called Scarborough the most influential Republican in America for being both among the first to predict Trump’s political rise and rebuke him.

Trump regularly called into “Morning Joe” during the early days of his candidacy and speak at length with Scarborough and Brzezinski, as The Washington Post has reported. One such time was in February 2016, after Trump won the New Hampshire primary.

“You guys have been supporters, and I really appreciate it,” Trump said. “And not necessarily supporters, but at least believers. You said there’s some potential there.”

Some early critics of Scarborough’s announcement were quick to point out his longtime friendship with Trump and willingness to give him a platform during the campaign.