Congressional Republicans attempting to doom the candidacy of one of President Biden’s nominees to the Federal Reserve’s board have a new, Democratic ally in their corner — Senator Manchin.

In order to prevent the nomination of Sarah Bloom Raskin from moving to the full Senate, the Republicans have been boycotting some meetings of the Senate Banking Committee, which needs to sign off on the president’s choice to be the country’s top banking regulator.

Ms. Raskin’s is part of a slate of five nominations, including that of Chairman Jerome Powell, that has been held up by the GOP senators’ protests.

The Republicans say they are concerned that Ms. Raskin will overly politicize the central bank’s regulatory activity. A former Fed governor now in academia, her research has focused on — among other things — the systemic risks posed by climate change.

They have also expressed concerns about Ms. Raskin’s efforts to secure a lucrative license for a financial technology firm, Reserve Trust, from the Fed after she left the bank and while she sat on the company’s board of directors.   

Mr. Manchin, who does not sit on the Senate Banking Committee but is a key vote in the evenly divided Senate, urged his fellow Democrats to move ahead with the slate of nominations without Ms. Raskin.

“If they’re willing to move four out of five? Take it and run with it. It’s a win,” the West Virginia Democrat told Politico.

In a tweet Thursday about rising inflation, Senator Toomey — the Pennsylvania Republican on the banking committee who has been leading the campaign against Ms. Raskin — reiterated his call for the president to withdraw the nomination and move on.

“As inflationary pressures grow and Russia continues waging war in Ukraine, the president must act to ease the pocketbook pain Americans are feeling,” Mr. Toomey said.

“The administration can start by reversing its disastrous anti-energy policies: restart the Keystone XL pipeline, expedite natural gas pipeline approvals, repeal its broad, punitive regulations on America’s oil and gas production, and withdraw the nomination of Sarah Bloom Raskin,” he added.

The banking committee’s lead Democrat, Senator Brown of Ohio, and the White House have both resisted the pressure to separate Ms. Raskin from the rest of the slate.

Speaking to reporters at the White House on Thursday, Press Secretary Jen Psaki said the Republicans are unfairly holding up the business of the Federal Reserve at a critical time. The Fed is widely expected to raise interest rates at its meeting next week in an effort to cool off an overheating economy.

“We believe all five nominees are eminently qualified and should be given an opportunity to be voted through the committee, where we … absolutely have the votes,” Ms. Psaki said. “Republicans are just not showing up to get quorum for … that vote to move forward.”

Mr. Toomey and the other Republicans on the committee have said they will support the other nominees on the slate, including Lael Brainard as vice chairwoman and economists Lisa Cook and Philip Jefferson as governors.