Former White House chief strategist Stephen Bannon is leading the charge to set up primary challenges against Republican senators who have crossed the Trump administration, Politico reported Sunday.

Besides courting millions in cash flow from conservative mega-donor Robert Mercer, Bannon has also been vowing his support to challengers who could usurp the seat from GOP incumbents, according to the news outlet.

Senior GOP lawmakers fear Bannon’s rising electoral revolt will pull away resources and millions of dollars that can be used to fight their Democratic rivals.

Senate Majority Leader Mitch McConnell Addison (Mitch) Mitchell McConnellMomentum growing among Republicans for Supreme Court vote before Election Day Trump expects to nominate woman to replace Ginsburg next week Video of Lindsey Graham arguing against nominating a Supreme Court justice in an election year goes viral MORE (R-Ky.) has warned the White House about the potential primary perils that could come about because of Bannon's mission, underscoring that the party’s narrow four-seat majority could be washed away by such efforts, three people with direct knowledge of the discussions told Politico.

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Bannon met with Heller rival Danny Tarkanian for 30 minutes on Thursday, in which Bannon vowed to fully endorse him as he runs against the Nevada senator who had refused to back Trump during last year’s campaign, according to Politico.

David Bossie, Trump’s former deputy campaign manager and the head of the conservative group Citizens United, is reportedly helping scout out possible primary challenger recruits to take on Flake.

Sources who are close to Bannon say he has also floated the possibility of finding challengers for Corker and Wicker, the report says.

The Breitbart News head similarly pushed for several insurgent primary challengers to go up against incumbents in the 2014 midterms.