Steve Bannon's target list

Looking at the voting histories of Bannon's targets, some things stand out for sitting Republican senators to consider: It doesn't seem to matter much how conservative you were before Trump came to office if you are not fully pro-Trump today. And it doesn't seem to matter how aligned your voting record is with Trump today if Bannon sees an opportunity to bring in someone who can be a louder, more consistent Trump advocate.

Every Republican senator up for re-election in 2018, with the exception of Sen. Ted Cruz of Texas, appears to be a target. Bannon also said he plans to back primary challengers in several other races where he thinks a crop of new Republican candidates can pick up seats for the GOP.

Bannon's thinking on this score is clear. Andy Surabian, a senior adviser to the Great America Alliance, the super PAC expected to support Bannon's candidates, told Breitbart News: "We're planning on building a broad anti-establishment coalition to replace the Republican Party of old with fresh new blood and fresh new ideas."

Specifically, Bannon says he wants Mitch McConnell deposed as Senate majority leader. He's asking for a pledge from every candidate he backs not to vote for McConnell as majority leader. This comes after a rough year between the White House and McConnell, including a major incident when the two reportedly screamed at each other.

Not just ideology or voting record

No Republican senator Bannon is targeting is more emblematic of the quest than Sen. Jeff Flake, the ardent Trump critic from Arizona.

Flake has conservative credentials -- he's "A rated" by the NRA, has a 100% National Right to Life score and can claim high scores on other conservative rankings -- but he's never fully embraced the Trump administration or its platform. In fact, he's pushed his fellow senators to rebel against it.

In July, Flake wrote an op-ed for Politico calling for Republicans to stand up to the President, reject his governing style and seek out a different economic philosophy than the economic nationalism espoused by Bannon. On top of that, he's hedged his support for Trump's wall and seemed to mock the President's lack of specifics for building it.

Common measures of voting history and ideology show Bannon is not afraid to go after even Republicans who generally agree with Trump on many issues. According to Nate Silver's Fivethirtyeight.com, Sens. Orrin Hatch of Utah, John Barrasso of Wyoming and Roger Wicker of Mississippi have voted in line with Trump at the highest rate in the Senate -- more than Cruz has.

By one popular measure of conservative ideology, DW-NOMINATE, Flake has the fourth-most conservative voting record histories among current Senate members. According to another, the Heritage Foundation's Scorecard, none of the members Bannon is challenging are outside of the Republican mainstream, with the possible exception of Hatch.

But these senators, all have the same flaw as Flake: They are not wild about Trump in one way or another. And this is what Bannon cannot tolerate. He wants the Senate to wholeheartedly embrace the President and believes it has to for Trump to govern effectively.

Hatch, the longest serving member of the Senate who has worked across the aisle with Democrats, epitomizes "The Establishment" Bannon rails against. He's criticized Trump on transgender rights, his response to Charlottesville and his tax plan goals. He's bristled with the Administration's plans for when to pass health care.

Flake and Nevada Sen. Dean Heller have waffled in their support of Trump while preparing for tough re-elections at home in purple states. Heller hedged his stance on Trump so much that he refused to confirm he voted for the President nearly a full year after the election.

Wicker and Barrasso, who have cast votes aligned to Trump's policies at the highest rate in the Senate, do not have strong records as vocal advocates for him. The same is true of Sen. Deb Fischer of Nebraska, who has voted less often with Trump's policies. In all six elections, Bannon sees the opportunity to replace senators who are either on the sidelines from or critical of Trump with hardline, loyal members.

The one exception, Cruz, is curious given his contentious history with Trump during the 2016 GOP primary. But he was the original pick in the 2016 primary of the Mercers, a prominent donor family with whom Bannon met to discuss funding opportunities for his political ambitions in 2018. And Cruz's conservative background is arguably stronger than any of the other candidates Banning is challenging.

All this said, even if Bannon does successfully lead a successful primary challenge against one of these Republicans, he'll still, depending on the state, have tough fights ahead in the general election. History suggests Democrats could have a strong election, despite defending far more seats than Republicans.