The Senate made Christopher Waller the first Federal Reserve Board nominee to be confirmed during a lame duck session, in a tight 48-47 vote Thursday.

Republican Sen. Rand Paul of Kentucky voted against Waller alongside the entire Democratic Conference, including five moderates who voted to advance his nomination out of the Senate Banking Committee: Sens. Jon Tester of Montana, Mark Warner of Virginia, Catherine Cortez Masto of Nevada, Kyrsten Sinema of Arizona and Doug Jones of Alabama.

“I think that President-elect Biden ought to have that appointment,” said Jones, who lost his reelection race.

Sinema’s office e-mailed a statement noting that her committee vote took place before the Treasury Department’s recent decision to end several Fed lending facilities designed to soften the economic blow of the COVID-19 pandemic.

“Coronavirus cases are rising in Arizona, and too many families and small business owners are struggling to stay afloat,” the statement said. “Given recent and unprecedented actions by the Treasury Department to terminate the Fed’s lending facilities and raise borrowing costs on Arizonans, the nominee’s unwillingness to support these lending facilities in his earlier confirmation hearing made clear he did not meet Senator Sinema’s criteria.”

Waller, a respected economist and the Federal Reserve Bank of St. Louis’ research director, was nominated in January with Judy Shelton, a controversial pick whose own nomination was narrowly blocked in November. Waller was picked to fill a seat vacated by Sarah Bloom Raskin with a term that ends in 2030.

With Waller’s confirmation, President-elect Joe Biden will only have one vacancy to fill on the seven-member Fed board. Biden’s choice would, if confirmed, be just the second Democrat on the Fed, joining Lael Brainard. While Waller is expected to be a conventional vote on interest rate decisions, his confirmation solidifies a conservative majority on regulatory matters.

Peter Conti-Brown, a Fed historian at the University of Pennsylvania’s Wharton School, has said Waller’s confirmation was the first during a lame-duck session in Fed board history.

Carl Tobias, a University of Richmond law professor who tracks Senate confirmations, thinks the close floor vote had little to do with views on Waller, but that Senate Democrats are just unwilling to confirm Trump nominees. “There’s no reason with Biden coming on to allow Trump to make any kind of appointment, especially one that carries a longer term,” Tobias said.

Rachel Oswald contributed to this story.