Former White House strategist Stephen K. Bannon revealed in a Sunday interview that he believes it will take decades to drain the swamp of Washington, D.C.

“The permanent political class, as represented by both parties … you’re not going to drain that in eight months,” Bannon said during an interview with CBS News anchor Charlie Rose for 60 Minutes. “You’re not going to drain it in two terms. This is going to take ten, 15, 20 years of relentlessly going after it.”

Bannon pointed out that nine of the most wealthy counties in the country circled Washington D.C., explaining that within 50 years, the permanent political class had turned it into big profits.

“The swamp is a business model,” he said, pointing to the political donors, consultants, K Street lobbyists, and politicians working in Washington, D.C.

Bannon recalled his first meeting with Trump and Senate Majority Mitch McConnell, where the senior Republican told them to stop saying that they were going to “drain the swamp.”

“‘I don’t want to hear any more of this “drain the swamp” talk,’” Bannon recalled McConnell saying.

Bannon’s 60 Minutes interview — his first since leaving the White House and returning as executive chairman of Breitbart News in August — aired Sunday night on CBS.