Former White House chief strategist Stephen Bannon alleges in a new interview that congressional GOP leaders are trying to undermine President Trump Donald John TrumpObama calls on Senate not to fill Ginsburg's vacancy until after election Planned Parenthood: 'The fate of our rights' depends on Ginsburg replacement Progressive group to spend M in ad campaign on Supreme Court vacancy MORE's agenda.

Bannon said in a "60 Minutes" interview excerpt released Thursday that it's "very obvious" that Speaker Paul Ryan Paul Davis RyanKenosha will be a good bellwether in 2020 At indoor rally, Pence says election runs through Wisconsin Juan Williams: Breaking down the debates MORE (R-Wis.) and Senate Majority Leader Mitch McConnell Addison (Mitch) Mitchell McConnellObama calls on Senate not to fill Ginsburg's vacancy until after election Planned Parenthood: 'The fate of our rights' depends on Ginsburg replacement Progressive group to spend M in ad campaign on Supreme Court vacancy MORE (R-Ky.) don't want Trump's "populist economic agenda" implemented.

"The Republican establishment is trying to nullify the 2016 election. That's a brutal fact we have to face," Bannon told CBS News in his first major interview since leaving the White House.

"I think Mitch McConnell, and to a degree, Paul Ryan," Bannon said when asked by interviewer Charlie Rose to specify who he claimed was trying to undermine Trump's agenda.

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"They do not want Donald Trump's populist, economic nationalist agenda to be implemented. It's very obvious," he said. "It's obvious as night follows day is what they're trying to do."

Bannon said that GOP leaders need to be "put on notice."

"They're going to be held accountable if they do not support the president of the United States. Right now there's no accountability. They have totally — they do not support the president's program. It's an open secret on Capitol Hill. Everybody in this city knows it."