Sen. Rand Paul (R-Ky.) is threatening to put a "hold" on the nomination of Janet Yellen to chair the Federal Reserve unless he gets a vote on his Fed transparency bill, according to CNBC's Steve Liesman.

"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 in a statement.

"The American people deserve transparency from the Federal Reserve and the federal government as a whole.”

A "hold" is an informal Senate procedure to signal a senator's intentions that he or she does not want a bill or nomination to reach the floor. In February, Paul put a hold on the nomination of John Brennan to be CIA Director while he awaited answers to questions about the U.S.' drone program. A few weeks later, Paul began his historic talking filibuster of Brennan's nomination.

Paul's intention to hold Yellen's nomination depends on whether fellow Senate Republicans go along with him. If Senate Majority Leader Harry Reid has 60 votes, Yellen's nomination will get through to a final confirmation vote.

"I don't know enough yet to know whether his request for a vote will be taken seriously, but I kind of doubt it," a Senate Democratic leadership aide told Business Insider.

This post has been updated.

