Sen. Rand Paul, R-Ky., is threatening to prevent Janet Yellen's nomination to be Federal Reserve Chair unless the Senate votes on his bill to audit the Fed.

"As part of Senate consideration of the Janet Yellen nomination to be Chair of the Federal Reserve, I will request a vote on my bipartisan Federal Reserve Transparency Act, S. 209," Paul said today in a statement. "The American people deserve transparency from the federal reserve and the federal government as a whole."

Paul's bill would require an audit to be conducted by the Comptroller General and have its findings and conclusions distributed to Congress.

Any senator can put a hold on a presidential nominee, and this was not the first time this approach has been used. Paul, like his father, former Rep. Ron Paul (R-Texas), has been highly critical of the Federal Reserve. It remains an open question to what lengths he will go to block her nomination.

"It is certainly appropriate for the Congress to monitor the job the Fed does, as the central bank is its creation. But I am not sure holding up Janet Yellen's appointment is the best way to do that," says Gregory Mankiw, who chaired President Bush's Council of Economic Advisers from 2003-2005 and now teaches at Harvard University. "The Fed needs a leader, and Janet is an excellent choice."

Currently, the Fed's activities, statements, and reports are monitored and reviewed by its own Inspector General, an independent outside auditor, as well as the Government Accountability Office.

In addition, Fed meeting transcripts and minutes are released to the public, and Fed governors are oftentimes called to testify before Congress.

The term of current Fed Chair Ben Bernanke ends on Jan. 31, 2014. A date for Yellen's hearing in front of the Senate Banking Committee has not yet been scheduled, though she is expected to have meetings with senators who will determine her fate. Yellen currently has meetings scheduled with Sens. Richard Shelby (R-Ala.), Elizabeth Warren (D-Mass.), Jon Tester (D-Mont.), Sherrod Brown (D-Ohio), Joe Manchin (D-W.Va.), Jeff Merkley (D-Ore.) and Dean Heller (R-Nev.).

Yellen is the first woman to be nominated to head the central bank and was nominated by President Obama after another candidate for the job, former Treasury Secretary Larry Summers, took himself out of the running amid criticism from both Democrats and Republicans. While Paul's hold will revive the debate on the Fed's transparency, Democratic lawmakers are likely to push hard to ensure that she is confirmed to the position.