Steve Bannon entered the 2018 election cycle vowing to run primary challengers against nearly every Republican incumbent, looking to shake the party establishment to its core.
The establishment, however, appears to have won.
Mr. Bannon took his latest blow Tuesday in Arizona, where former state Sen. Kelli Ward, one of his earliest recruits, fell to Rep. Martha McSally, a more establishment-minded candidate, in the battle for the Republican nomination to replace retiring Sen. Jeff Flake.
Her loss followed similar failures by Bannon-backed candidates in Wisconsin, where his Senate pick lost in a primary this month, in Nevada, where his preferred Senate candidate dropped out and is running for a lower office, and in Alabama, where Roy Moore squandered a seat long held by Republicans in a special election late last year.
Prince William Board of Supervisors Chairman Corey A. Stewart, meanwhile, eked out a primary win in Virginia, and Mr. Bannon backed winners in Senate Republican primaries in Tennessee, West Virginia and Montana, where the candidates were established political figures before Mr. Bannon gave them his blessing.
But political observers say Mr. Bannon usually came up short in races where tried to play kingmaker.
“The problem is that the ones that Bannon tried to mold or had a hand in molding wound up failing and the ones that were the best options to begin with or well-known in their states wound up winning,” said Ford O’Connell, a Republican Party strategist.
Mr. O’Connell said the Trump world appears to have settled on a strategy of backing candidates they believe are best-equipped to win competitive general election races and when possible get behind Trump-like candidates.
Mr. Bannon, who was Mr. Trump’s top strategist until his ouster from the White House a year ago, did not return an email seeking comment.
Mr. Stewart, the Republican senatorial candidate in Virginia, cautioned against reading too much into individual races because Mr. Bannon’s influence over time remains to be seen.
“I certainly do think that he is kind of the intellectual foundation for the emerging Trump wing of the party,” Mr. Stewart said.
“There is no question that there is this division within the Republican Party between the old establishment traditional conservative wing of the party and the emerging Trump working-class wing that wants to embrace working-class issues — namely illegal immigration and international trade issues — and that is not going away,” he said. “It may not happen in some massive revolt in 2018, but it is definitely happening.”
Mississippi state Sen. Chris McDaniel, who caught Mr. Bannon’s attention during his insurgent bid against Sen. Thad Cochran in 2014, said the rebellion that rose up before Mr. Trump arrived is thriving in his state, where he is running against Sen. Cindy Hyde-Smith.
“Our fight against the establishment is a continuation of what we started so many years ago, and we don’t anticipate it is going to end anytime soon,” Mr. McDaniel said.
Mrs. Ward’s loss is particularly stinging for Mr. Bannon, who endorsed the former Arizona state senator nearly a year ago as he announced his plans to build a “grassroots army” intent on making the party’s establishment “reap the whirlwind.”
“It is going to be their money versus your muscle,” Mr. Bannon said at the time.
Running as a die-hard Trump backer, Mrs. Ward was financially outgunned by Ms. McSally, who raised more than $1 million over the closing weeks of the campaign and spent $3.3 million. That more than doubled Mrs. Ward’s financial haul.
Ms. McSally also enjoyed strong support from outside groups, while KelliPAC, a super political action committee backing Mrs. Ward, used up its cash.
It spent $215,000 more than it raised through the end of July, according to finance reports that showed the last cash infusion of $500,000 came in late June from Robert Mercer.
The hedge fund billionaire and major Trump backer cut ties with Mr. Bannon this year after his public split with the president, who stayed on the sidelines in the Arizona primary race.
Ms. McSally held 53 percent of the vote to Mrs. Ward’s 28 percent. Former Maricopa County Sheriff Joe Arpaio was third with 19 percent. Conservatives said the race would have been more competitive if he had dropped out and given Mrs. Ward a cleaner battle against Ms. McSally.
Mrs. Ward also was on the defensive over the final days of the race after her campaign suggested it was fishy that Sen. John McCain’s family announced Friday that he was ending medical treatment, coinciding with the start of her bus tour.
Mr. McCain died a day later, sparking an outpouring of tributes to him — and leaving Mrs. Ward to apologize and blame the press for peddling a “false narrative.”
Mr. Bannon’s biggest hope now for ousting a sitting Republican is Mr. McDaniel’s challenge of Mrs. Hyde-Smith in a special election in November to fill out the term of Mr. Cochran, who retired this year.
Mr. McDaniel first set his sights on taking out Republican Sen. Roger F. Wicker, another top Bannon target. But his bid got off to a rough start when Mr. Trump endorsed Mr. Wicker on the eve of Mr. McDaniel’s campaign launch.
Things haven’t gotten easier for Mr. McDaniel since he announced he was changing gears to run for Mr. Cochran’s former seat. Gov. Phil Bryant, a Republican, appointed Mrs. Hyde-Smith to the seat on an interim basis in March.
Last week, Mr. Trump endorsed Mrs. Hyde-Smith.
The president also endorsed incumbent Sen. Dean Heller in Nevada, helping to chase away a challenge from Bannon-backed Danny Tarkanian, who is now running for an open House seat, and Sens. John Barrasso in Wyoming and Deb Fischer in Nebraska.
Mr. McDaniel downplayed the endorsement, saying Mr. Trump felt the need to cut a deal with Senate Majority Leader Mitch McConnell, Kentucky Republican, in an attempt to advance parts of his agenda that have stalled.
“We want to send a strong outsider to Washington so President Trump never again has to cut a deal with Mitch McConnell and that he can lead the charge without being worried about obstruction in the Senate,” Mr. McDaniel said.
As for Mr. Bannon’s influence, Mr. McDaniel said it is “hard to gauge.”
“Politics is a strange profession. One day it appears that a person is on top of the world; the next day they are in the valley,” Mr. McDaniel said. “But there is also a chance for resurrection.”
Sources familiar with Mr. Bannon’s thinking said he has turned his focus to thwarting Democrats who have called for the impeachment of Mr. Trump and urged voters to go as far as to elect “RINOs,” or Republicans in name only, to prevent that from happening.
“We are at war with the progressive left for the MAGA agenda,” a source close to Mr. Bannon said. “You fight with the troops you have, not the troops you want.
“Bannon has been adamant that the only thing that matters is a Trump victory on 6 Nov. and the populist movement must close ranks behind moderate candidates including RINOs” the source said. “This is a referendum on Trump — and it’s now all hands on deck.”
The New York Times reported this month that Mr. Bannon also is trying to put his imprint on the elections through Citizens of the American Republic, a group he is forming to drive home the message that Mr. Trump’s agenda is on the line in the midterm elections.
“More than any other midterm, this is a referendum on his style and on his content, and you cannot run from that; you have to embrace it,” Mr. Bannon told the newspaper.