Paul is insisting on a vote on his Fed transparency bill, and has informed Senate leadership of his intentions, the source said.
(Watch: Rand Paul says 'audit the Fed' )
A Senate Democratic aide told CNBC this morning that the ability of Paul to single-handedly block the nomination "should not be overstated." Paul would need 40 other senators to join him to cut off a motion to end debate and bring the nomination to the floor. Although hearings have not yet been scheduled, the aide said the leadership at this point is confident the nomination will succeed. (Read more below the video.)
Paul intends to formally put the hold in place next week, once the Senate is back in session, the source added.
Markets gave back some of their earlier gains on the report. ( Click here for the latest on the markets).
The senator's bill would mandate a complete audit of the Federal Reserve.
According to his website, his bill is a version of legislation advocated by his father, the former Texas congressman and presidential candidate Ron Paul.More From CNBC
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