It was a time of choosing.
The rift that ripped wide open Wednesday between President Trump and his former top adviser Steve Bannon forced the populist movement they both strive to lead to take measure of the two men, though the president retained a clear advantage.
Mr. Bannon’s political clout stems from Mr. Trump, not the other way around, said Republican strategist Chris Wilson, but he also called the dust-up an unnecessary distraction for the White House.
“A lot of [Mr. Bannon’s ] strength comes from representing the Trump base, and right now that Trump base is called the Trump base for a reason. It’s the Trump base and not the Steve Bannon base,” he said.
At the same time, Mr. Bannon will continue to have followers and a platform for his political agenda at Brietbart News, where he retuned to his job as executive chairman after being fired from the White House in August.
“You are going to find people who are loyal to both,” Mr. Wilson said.
Since his exit from the White House, Mr. Bannon assumed the role of kingmaker for the Trump movement, backing candidates he deemed pro-Trump and anti-Republican establishment.
The move created tension with the White House, including when Mr. Bannon and Mr. Trump backed opposing candidates in the Republican primary race in Alabama for U.S. Senate and Mr. Bannon’s pick ultimately cost the party the usually safe Senate seat.
Senate Majority Leader Mitch McConnell of Kentucky, who embodies the Republican Party establishment, has warned that Mr. Bannon’s crusade would only help elect Democrats.
“The establishment Republicans are happy because now Trump sees that Bannon has been a liability all along,” said Republican Party strategist Ford O’Connell.
Mr. Trump on Wednesday slammed Mr. Bannon after the former adviser was quoted in a book saying that a Trump Tower meeting in 2016 between Donald Trump Jr. and a group of Russians was “treasonous” and “unpatriotic.”
“When he was fired, he not only lost his job, he lost his mind,” Mr. Trump said in a statement released by the White House.
He accused Mr. Bannon of not representing the Trump base, saying his former adviser was “only in it for himself,” and he called Mr. Bannon a secret ally of news media that oppose the administration.
Ari Fleischer, who served as press secretary for President George W. Bush, faulted Mr. Bannon for positioning himself as an alternative to the president’s leadership.
“Bannon needs either to deny what’s written in the book, or primary Trump for President. There’s really not much ground in between,” he wrote on Twitter.
Later, Mr. Bannon attempted to distance himself from the reports about his comments on Donald Trump Jr. and the Russians, but he did not deny making the statements.
“This is total Fake News and taken out of context, don’t believe the liberal propaganda Machine! #MAGA,” he said in a tweet, making sure to include the hashtag for Mr. Trump’s campaign slogan.
The comments posted on the Brietbart site for an article about Mr. Trump blasting Mr. Bannon tilted decidedly in favor of the president.
“Bannon has blown it. He took an important and brilliant point of view and turned it into a Trump trash talking disgrace. I support our President,” wrote a reader with the screen name geoffyjoe.
Donald Trump Jr. noted the trend.
“Wow, Just looked at the comments section on Breitbart. Wow. When Bannon has lost Breitbart, he’s left with umm, nothing,” he tweeted.
Mr. Bannon suffered a similar backlash in comments on Breitbart after his candidate in Alabama’s race for Senate, Roy Moore, was defeated by Democrat Doug Jones, who was sworn into office Wednesday.
Mr. Bannon had been a powerful figure in the Trump-inspired populist movement, and his endorsements at one time were prized by Republican candidates, especially in Senate races.
The White House insists the president’s base is intact.
“The president’s base is very solid. It hasn’t changed because the president hasn’t changed and his agenda hasn’t changed,” said White House press secretary Sarah Huckabee Sanders. “The president’s still exactly who he was yesterday — as he was two years ago, when he started out on the campaign trail.”
The Trump-Bannon feud spilled over into the midterm election campaign in West Virginia, where Republican primary opponents clashed over who is allied with the president and who is allied with Mr. Bannon.
Rep. Evan H. Jenkins sided with Mr. Trump and called on Attorney General Patrick Morrisey, a top rival, do the same.
“After Steve Bannon’s vicious attacks on President Trump and his family, Patrick Morrisey should immediately disavow Bannon’s support,” Mr. Jenkins said in a press release. “If he refuses, West Virginians will know that what President Trump said of Bannon today is also true of Morrisey: ‘He is only in it for himself.’”
The Morrisey camp, which celebrated Mr. Bannon’s endorsement months ago, brushed off the demand.
“Attorney General Morrisey does not support these attacks on President Trump and his family, and was proud to stand with President Trump in 2016 when they were both overwhelmingly elected in West Virginia and when he cast his vote for Trump in the Electoral College,” said Morrisey campaign spokesman Nachama Soloveichik. “Evan Jenkins is a fraud who supported Hillary Clinton in 2008 and stood by Barack Obama for years while Obama ran roughshod over West Virginia.”
Other candidates labored to avoid choosing sides.
“It is just like two brothers fighting. They’ll get over it. But, you know, obviously it got a little personal,” said Corey Stewart, who is running for the Republican nomination in the U.S. Senate race in Virginia.
Mr. Stewart was the Trump campaign’s Virginia state chairman until he was fired in October 2016 for participating in a pro-Trump protest in front of a Republican National Committee headquarters.
He has received strong support from Mr. Bannon in the Senate race and said he still welcomes the support and would welcome support from Mr. Trump as well.
Asked if he considers himself a Trump Republican or Bannon Republican, Mr. Stewart claimed that there was no difference.
“It is one and the same,” he said. “There is a little personal dispute going on here between the two of them, but they are really both part of the same movement.”
• Seth McLaughlin and Dave Boyer contributed to this report.