Former White House chief strategist Steve Bannon is increasingly expanding his proclaimed “season of war” against establishment Senate Republicans to include primary races in states with Democratic incumbents, hoping to sway GOP challengers toward his nationalist/populist movement and against Majority Leader Mitch McConnell.

In some cases, including in Montana and Missouri, Bannon’s preferred candidates are also the top recruits of McConnell and the Senate Republicans’ campaign arm. In others, Bannon is courting candidates in competitive and divisive races, hoping to help elect those aligned with his policy goals.

The iconoclastic conservative met in Washington last week with Pennsylvania Rep. Lou Barletta (pictured), a top Trump supporter considered the front-runner in a crowded primary to challenge Democratic Sen. Bob Casey. (He also met with businessman Jeff Bartos, another candidate in that race, while still working at the White House.) In Indiana, Rep. Todd Rokita and state Rep. Mike Braun have reached out to Bannon about setting up meetings, and one with Braun is expected to take place soon, according to a source familiar with the planning. Both candidates hope to unseat Democratic Sen. Joe Donnelly.

He’s also been in regular phone contact with Robert Ritchie -- known professionally as Kid Rock -- about the musician’s potential campaign against Sen. Debbie Stabenow, a source familiar with the conversations told RCP. (A publicist for Ritchie wouldn’t confirm the conversations in an email, but said they would have an announcement “soon!”)

In addition to those meetings, Great America PAC, a group aligned with Bannon, has endorsed candidates in primary races in West Virginia and Wisconsin, where popular Democrats are seeking re-election. The PAC has also endorsed in Tennessee and Arizona, two states with incumbent GOP senators. Bannon attacked and criticized McConnell extensively during an event Tuesday for former Arizona state Sen. Kelli Ward, who is challenging Sen. Jeff Flake.

“It’s an open revolt, and it should be,” Bannon said, later adding, “We’re building a grassroots army. It’s going to be their money versus your muscle.”

Many Republicans who oppose Bannon’s moves against GOP incumbents have argued that they won’t be effective against senators who have backed Trump’s agenda and are well known at home. McConnell allies were pleased when Trump said during a lengthy press conference with the Kentucky lawmaker Monday that he might try to talk Bannon out of challenging some incumbents -- and McConnell’s super PAC, Senate Leadership Fund, raised $7.1 million in the third quarter.

But McConnell added that the goal is to “nominate people who can actually win in November.” Josh Holmes, a former chief of staff to the majority leader, said Bannon’s influence in races against Democratic incumbents could cause serious problems for Republicans in next year’s midterms.

“There are candidates who have extremely good outlooks for general election success today that are unfortunately flirting with picking up a whole hell of a lot of liabilities unnecessarily by associating with Steve Bannon,” Holmes said. “I think Steve Bannon is an incredible liability. He is not an asset anywhere.”

Though Bannon has declared war on the party establishment, he’s singled out McConnell as the main target. In almost every case, candidates that have met with, sought to meet with, or been endorsed by Bannon have either openly opposed McConnell remaining as the GOP leader or have declined to weigh in on his future.

“We know that Bob Casey will not repeal Obamacare or reform the tax code. We also know that, to date, Mitch McConnell cannot,” Bartos, the Pennsylvania candidate, wrote in an op-ed to be published Thursday. “Until the dysfunctional Senate leadership shows that they can deliver for the people who support the president’s agenda, I will not pledge to vote for Mitch McConnell for Republican Leader.”

Others have avoided the question altogether. Spokespeople for Barletta did not respond to multiple requests for comment on his meeting with Bannon; both Rokita and Rep. Luke Messer, the two House members running for Senate in Indiana, hedged when asked about their support for McConnell.

“I’m so focused on our own primary I haven’t spent a lot of time thinking about that,” Messer said in an interview late last month. (A spokesman didn’t return emails Wednesday asking if he still holds that view.) “The biggest issue in my primary is folks want to see a Senate that’s supportive of President Trump’s agenda, and that’s what I intend to do when I get an opportunity to serve in the United States Senate.”

When asked about support for McConnell, Nathan Brand, a spokesman for Rokita’s campaign, said, “Republicans in Indiana are united around the fact that Joe Donnelly does not share Hoosier values. Washington elites like Donnelly are the problem in the Senate.”

McClatchy reported Tuesday that Missouri Attorney General Josh Hawley, the top recruit to challenge Sen. Claire McCaskill, wouldn’t directly address whether he’d support the party leader.

Ohio state Treasurer Josh Mandel, who is running against Sen. Sherrod Brown after losing to him five years ago, declined to discuss whether he’d support McConnell in a press conference Tuesday.

“We’ll be glad to, you know, address elections that happen a year and a half from now after we beat Sherrod Brown,” Mandel said. Though the challenger has support from across the party -- McConnell’s super PAC backed his first run and he’s been endorsed by Sen. Rob Portman, the conservative Club for Growth and others -- a source close to Bannon said other options could be explored if Mandel doesn’t oppose McConnell.

“The sole reason Mandel has yet to receive support from Steve is his refusal to publicly take a stand against McConnell,” the source said.

Meanwhile, Wisconsin Democrat-turned-Republican Kevin Nicholson won support from Bannon in his bid to unseat Sen. Tammy Baldwin, and his campaign has said he would not support McConnell. Nicholson is running in the GOP primary against state Sen. Leah Vukmir, who has touted her work in the legislature with Gov. Scott Walker. Vukmir told the Associated Press that she met with Bannon, but support for McConnell did not come up. In the interview with the AP, Vukmir would not say indicate her stance on the majority leader.

“‘The Steve Bannon primary in Wisconsin is over and Kevin Nicholson has won.’ Humbled by this huge endorsement,” Nicholson, a former Marine, wrote on Twitter, quoting the lead in Milwaukee Journal Sentinel story.

West Virginia Attorney General Patrick Morrisey also welcomed Bannon’s support after the two had conversations about the primary race to take on Democratic Sen. Joe Manchin.

“He obviously has a very loud bullhorn to help get our message out, and he has a lot of donors and relationship that could be very helpful,” said a Morrisey adviser. “It says to voters, ‘Hey, we're the legitimate conservative in this race, endorsed by an imprimatur of Trump.’”

Morrissey is running against Republican Rep. Evan Jenkins in what figures to be a long and bitter primary fight.

While an endorsement from Bannon and the pro-Trump PAC is coveted in West Virginia, where Trump enjoys his highest approval ratings, it’s unclear exactly how consequential it could be in terms of moving votes. “I don't know if anyone knows yet,” said the adviser. “I don't know if they're going to spend money or run independent expenditures. They have the ability to be very helpful if they want.”

When assessing Bannon’s influence, some strategists have noted his lack of experience when it comes to actually running campaigns and organizing on the ground. They point to candidates that Breitbart, the news outlet Bannon leads, has promoted who have failed in the past.

They also question the stability of the insurgent campaigns. When Bannon traveled to Arizona for a rally for Kelli Ward, her campaign was undergoing a bit of drama. Two of Ward's campaign staffers, her political strategist and press secretary, quit last month and released a scathing statement this week condemning her candidacy. Meanwhile, a new Fox News poll showed the Senate race tightening in Alabama, where Bannon campaigned for the primary runoff victor, Roy Moore. The survey finds Democrat Doug Jones tied with Moore at 42 percent.

And while Trump won key battlegrounds like Wisconsin, some wonder whether midterm candidates will face a dynamic different from 2016’s.

“In a state where the primary vote next year is really more establishment Republicans, I don't see that the Bannon endorsement means a bucket worth of anything,” says Wisconsin GOP consultant Brandon Scholz. “I just don't see boots on the ground.”

The Great America PAC is aiming to help on the organizational front. Ed Rollins, a veteran Republican and the group’s lead strategist, says he is encouraging Bannon to select candidates who have the ability to establish a viable campaign infrastructure and who can win.

“Trump's numbers work for him,” he said, “but is 40 percent [approval] enough to get a senator elected? No, it's not. Every Senate campaign needs to build out.”

The upcoming battle on tax reform in Congress figures to be key in determining the viability of insurgent campaigns. Still reeling from the GOP’s failure to repeal Obamacare, strategists from various factions of the party seem to agree that failure to pass legislation to alter the tax code could doom incumbents and empower challengers.

Bernie Marcus, the co-founder of Home Depot and a longtime GOP donor, is warning Republicans about losing power after the midterms. “If people who make promises don't fulfill them, they should be out of Congress,” he told RCP.

Bannon has spoken with Marcus, as first reported by Politico, but the businessman is waiting to see whether Republicans can deliver before he decides on investing in congressional races. “He’s very passionate, but I'm not a follower for the sake of being a follower,” Marcus said of Bannon, adding that he wished he would focus on the Democrats. “If [Republicans in Congress] produce, I will support them. If not, I will find another way to go.”

“McConnell has an [opportunity] to redeem himself by bringing the party together,” said Marcus, who founded the Job Creators Network to push tax reform. “McConnell is a very industrious guy, and a bright guy, but if he can’t get it done, somebody should replace him.”

James Arkin is a congressional reporter for RealClearPolitics. He can be reached at jarkin@realclearpolitics.com. Follow him on Twitter @JamesArkin.