Former White House chief strategist Steve Bannon said the Trump administration's biggest mistake came early on when they dropped their "drain the swamp" attitude for the sake of simply forming a government.

"In the 48 hours after we won, there's a fundamental decision that was made," Bannon said to Charlie Rose in a "60 Minutes" interview. "You might call it the original sin of the administration. We embraced the establishment. I mean, we totally embraced the establishment."

Bannon said many of the people that had staffed the backbone of the campaign — including himself — comprised an "island of misfit toys."

"So he looks around and I'm wearin' my combat jacket, I haven't shaved, I got — you know, my hair's down to here, and he says — he's — he's thinkin,' "Hey, I've gotta put together a government. I've gotta really staff up somethin'. I need to embrace the establishment."

Bannon told Rose that the task of "draining the swamp" was a bigger accomplishment than any one administration could pull off, predicting it would 15-20 years of "relentlessly going after it."

Bannon, once again the chief editor of Breitbart News, also related a story about how Senate Majority Leader Mitch McConnell complained about the "swamp" language, arguing that he was having a difficult time convincing the right people to take government jobs in D.C. and on Capitol Hill because of the pay, reporting requirements, and scrutiny.

Bannon's wide-ranging discussion with Rose is his first "extended" mainstream media interview since leaving the White House on Aug. 18.

On the same day as the news of his departure broke, Bannon had a harsh prediction for the rest of the Trump presidency.

"The Trump presidency that we fought for, and won, is over," Bannon told The Weekly Standard. "We still have a huge movement, and we will make something of this Trump presidency. But that presidency is over. It'll be something else. And there'll be all kinds of fights, and there'll be good days and bad days, but that presidency is over."

Other excerpts of the Bannon interview were released in recent days by CBS, which included Bannon saying National Economic Council Director Gary Cohn should have resigned over his feelings about the Charlottesville, Va., riots and Trump's response, and also Bannon saying that the Catholic church has an "economic interest" in fostering illegal immigration into the United States.

The interview does not touch on the recent deal President Trump struck with congressional Democrats to extend the deadline on the debt ceiling by three months.