President Trump's controversial chief strategist Steve Bannon is leaving the White House, in another major staff shakeup announced at the close of another tumultuous week in Washington.

The White House confirmed in a brief statement that Bannon, a hardcore populist who often sparred with his West Wing colleagues, would make Friday his last day -- just over a year after he joined the Trump presidential campaign.

"White House Chief of Staff John Kelly and Steve Bannon have mutually agreed today would be Steve's last day," White House Press Secretary Sarah Sanders said in a statement. "We are grateful for his service and wish him the best."

One White House aide told Fox News the departure was a long time coming, and that Bannon actually submitted his resignation in writing two weeks ago.

In this photo taken April 29, 2017, Steve Bannon, chief White House strategist to President Donald Trump is seen in Harrisburg, Pa. The Campaign Legal Center is complaining in a letter to the White House that Bannon may be illegally accepting outside professional services.(AP Photo/Carolyn Kaster) (AP)

This would have been just days after Kelly joined as chief of staff. Kelly was said to have been the driving force in the ouster of former communications director Anthony Scaramucci, and speculation swiftly centered on Bannon as the next one to go.

Sources say Bannon has become increasingly isolated in the White House. Adding to the pressure, some critics also publicly attacked Bannon in the wake of last weekend's Charlottesville violence, in which a counter-protester was killed at a white nationalist rally. Trump came under intense criticism for his response to that violence, and some blamed Bannon for the tone -- though it's unclear how much influence he had in Trump's remarks.

Bannon formally joined Trump’s team last summer, when the former head of Breitbart News was tapped as chief executive of the campaign. After Trump won the presidential race, Bannon was appointed to a senior adviser role at the same time Reince Priebus was named chief of staff.

The Drudge Report first reported Bannon’s exit, saying he could return to Breitbart.

Earlier this week, Bannon gave a candid interview to a liberal magazine where he slammed some of his adversaries inside the administration.

Speaking to The American Prospect, Bannon contradicted the administration's statements on North Korea. He said despite threats to attack the regime, "There's no military solution [to North Korea's nuclear threats], forget it."

Secretary of State Rex Tillerson and Defense Secretary Jim Mattis on Thursday rebuffed those remarks.

Bannon has long been a target of mainstream Republican ire – and until now had survived even as top Trump lieutenants like Sean Spicer and Priebus have resigned.

Trump briefly addressed the speculation about Bannon's future during a wide-ranging Q&A with reporters at Trump Tower on Tuesday afternoon.

“I like Mr. Bannon, he’s a friend of mine,” Trump said, while downplaying his impact in the 2016 campaign. “I like him. He’s a good man. He’s not a racist … but we’ll see what happens with Mr. Bannon.”

The departure eased criticism of the administration only slightly.

The Democratic National Committee reacted to the news by saying there “is one less white supremacist in the White House, but that doesn't change the man sitting behind the Resolute desk.”

Some conservatives expressed worry in recent days about Bannon’s potential departure.

“Since the first day they joined the Trump campaign there have been two people we conservatives could rely upon to share our ideas and values and take our concerns and issues directly to Donald Trump: Kellyanne Conway and Steve Bannon,” conservative activist Richard Viguerie wrote to his email list this week.

During his time at the White House, Bannon clashed with National Security Adviser H.R. McMaster and National Economic Council Chairman Gary Cohn.

On Thursday, longtime Trump adviser Roger Stone wrote a column saying that while he liked Bannon, he thought it was time for him to go.

“I am one who had publicly defended Bannon from false charges of racism and anti-Semitism yet I have concluded he is a spent force, never being willing to spend his political capital to help his friends and in some cases helping empower the very globalists he claims to oppose,” Stone said.

Fox News' Brooke Singman, John Roberts and Serafin Gomez contributed to this report.