A Republican-led effort to overturn President Joe Biden's COVID-19 vaccine mandate or test rule for private sector businesses with more than 100 employees was successful on Wednesday, delivering the GOP a major victory – albeit a largely symbolic one, as the measure is unlikely to advance further.

The final vote was 52-48, with two moderate Democrats – West Virginia Sen. Joe Manchin and Montana Sen. Jon Tester – joining all 50 Senate Republicans voting to nullify the measure. The measure now heads to the House, where it is unlikely to be considered.

What You Need To Know

  • Senate Republicans could score a big symbolic victory if a GOP-led resolution to nullify President Joe Biden's COVID-19 vaccine mandate or test for private sector businesses

  • The victory is largely symbolic, as the measure is unlikely to pass the House, and President Joe Biden will veto the measure should it reach his desk

  • A federal judge temporarily blocked the rule in November and the multiple challenges to the mandate were consolidated into one, which will be heard by the 6th U.S. Circuit Court of Appeals, based in Ohio
  • The final vote was 52-48, with two moderate Democrats joining all 50 Senate Republicans voting to nullify the measure

Biden announced the new rule back in September which required businesses with more than 100 employees to mandate COVID-19 vaccines for their workforce, or submit to weekly testing and strict masking requirements. The rule, issued last month, was set to go into effect in early January, but prompted several lawsuits, largely from Republican-led states. 

A federal judge temporarily blocked the rule in November and the multiple challenges to the mandate were consolidated into one, which will be heard by the 6th U.S. Circuit Court of Appeals, based in Ohio.

The challenge, led by Indiana Sen. Mike Braun, was introduced in mid-November and sought to challenge Biden's mandate under the Congressional Review Act, which allows Congress to challenge a rule set forth by the executive branch. 

The victory by Republicans is largely symbolic: It's unclear whether the Democrat-led House would even bring the measure up for a vote.

Republicans in the House could vote on a procedure to force a vote, but it's unclear whether they would have enough support to do so – much less for such a measure to pass the Democrat-controlled chamber.

And in the somewhat unlikely event it passes both the House and the Senate, it would be vetoed by President Biden, White House press secretary Jen Psaki said Tuesday.

"We certainly hope the Senate, Congress will stand up to the anti-vaccine and testing crowd," Psaki said. "We're going to continue to work to implement these."

"Our view and the view of many Americans is that if people aren’t vaccinated, having them test once a week is quite reasonable as we’re thinking about how to protect our workplaces, how to protect stores and retail locations as people are out shopping for Christmas and the holidays, how to protect schools and public places," Psaki added. "And we also know that more than 100 leading public health experts have endorsed this rule."

"If it comes to the president's desk, he will veto it," Psaki said.

But those long odds did not stop Republicans in the Senate.

"I am pro-vaccine, but I am anti-mandate," Wyoming Sen. John Barrasso, a physician, said at a press conference Wednesday. "I believe the mandate is a massive overreach by the government and a massive mistake."

Challenges using the Congressional Review Act only require a simple majority in the Senate – and Democratic defections from West Virginia Sen. Joe Manchin and Montana Sen. Jon Tester signaled earlier Wednesday that it was all but certain to pass.

"I do not support any government vaccine mandate on private businesses," Manchin said in a statement explaining why he co-sponsored the bill to overturn the mandate. "I have long said we should incentivize, not penalize, private employers whose responsibility it is to protect their employees from COVID-19. I have personally had both vaccine doses and a booster shot and I continue to urge every West Virginian to get vaccinated themselves."

"Over the past few months, I’ve repeatedly heard concerns from Montana’s small business and community leaders about the negative effect the private business vaccine mandate will have on their bottom lines and our state’s economy," Tester said in a statement of his own. "That’s why I intend to join a bipartisan majority of my colleagues in defending Montana jobs and small businesses against these burdensome regulations. I strongly urge every eligible Montanan to get vaccinated as soon as possible so we can end this pandemic once and for all."

Braun told MSNBC that he's spoken to other Democrats who might also vote in favor of the resolution overturning the mandate.

"Anybody that is listening to their people back home, this doesn't poll when it's vaccine or job," the Indiana lawmaker told the network. "Even when you say vaccine or get tested or job, most of the people that are digging in regardless of their reasons aren't viewing it as an option."

Senate Majority Leader Chuck Schumer, D-N.Y., slammed the vote on Wednesday, calling it "anti-science" and "anti-common sense."

"I will strongly vote against this measure,with strong feelings about what’s good for this country and about fighting anti-science and theories that seem to," Schumer said on the Senate floor earlier in the day, ahead of the vote. "Anti-science, non-science, fictional belief comes from there. We ought not give it a stamp of approval in this chamber."