The Senate failed to advance the nomination of Judy Shelton to the Federal Reserve Board — further complicating what was an already rocky confirmation process.

Shelton, a longtime Fed critic who favors a return to the gold standard, was blocked in a 50-47 vote that was shaken up by some GOP senators being absent and Vice President-elect Kamala Harris making a return to the Senate floor.

Senate Majority Leader Mitch McConnell (R-Ky.) needed just 50 Republicans to vote in favor of Shelton to move her nomination forward.

The upper house of Congress currently has a 53-47 GOP majority, meaning that McConnell could afford to lose three votes to push Shelton through. If a 50-50 tie emerged, Vice President Mike Pence would be able to vote in favor and break the tie.

McConnell was dealt multiple blows ahead of the vote. Republicans Mitt Romney of Utah, Susan Collins of Maine and Lamar Alexander of Tennessee all vowed to oppose Shelton.

Then Sens. Chuck Grassley (R-Iowa) and Rick Scott (R-Fla.), both of whom supported Shelton’s nomination, were unable to vote because they were quarantining due to the coronavirus. Grassley had tested positive while Scott had been exposed.

In another twist, Alexander said Monday he would be unable to vote on Shelton’s nomination because he had been called away on what his spokesman described as “family matters.”

To help the Democrats block the nomination, Harris returned to the Senate floor in her capacity as a California senator to vote against Shelton, helping push them over the edge.

“Senator Harris knows this is an important vote, and she’s here for it. She didn’t need contacting,” Senate Minority Leader Chuck Schumer (D-NY) told reporters of her return.

McConnell himself voted against Shelton, a tactic which, for procedural reasons, gives him the ability to bring the nomination back for another vote.

If he chooses to bring Shelton’s nomination up for a vote again, he will face a new impediment: a single incoming Democratic senator.

Sen.-elect Mark Kelly (D-Ariz.) will be sworn in and replace Sen. Martha McSally (R-Ariz.) when the Senate returns after Thanksgiving to serve out the remainder of the late Sen. John McCain’s term.

Kelly is largely expected to oppose Shelton’s nomination.

Her nomination was approved by the Senate Banking Committee in July on a 13-12 party-line vote. Another President Trump nominee, Christopher Waller, was approved at the same time 18-7.

Shelton’s views on interest rates have moved in lock step with Trump’s. She has also expressed skepticism over the Fed’s need to set policy independently from the president and Congress.

The US abandoned the gold standard, a system in which currency is backed by gold, in 1933 during the Depression when Congress enacted a resolution nullifying the right of creditors to demand payments in gold.