WASHINGTON (AP) — A top Senate Republican on Tuesday said conservative economist Judy Shelton does not have the votes to be confirmed to one of two vacancies on the Federal Reserve board.

Sen. John Thune of South Dakota, who holds the No. 2 spot in the Senate Republican leadership, said Shelton's nomination will not be brought up until the votes are there.

"We're still working it," he told reporters after a weekly Republican lunch. "She's a priority for the White House. It's the Federal Reserve. It's important, so obviously we want to get it done. But we're not going to bring it up until we have the votes to confirm her."

Shelton's nomination cleared the Senate Banking Committee earlier this year on a straight party-line vote of 13-12, with Democrats opposing the nomination. They contend that her views are too far out of the mainstream for the seven-member Fed board, which currently has two vacancies.

President Donald Trump nominated Shelton and Christopher Waller, the research director at the Federal Reserve's regional bank in St. Louis, for two vacancies. If both win confirmation, the president will have installed six of the seven board members including elevating Republican Jerome Powell, originally an Obama selection, to be Fed chairman.

While Waller is viewed as a credible choice, Shelton has proven controversial because of her past views, including advocating a return to the gold standard, which most mainstream economists see as unworkable.

At her confirmation hearing, Shelton said she supports the Fed's independence from political meddling but she defended the sharp attacks Trump has frequently launched against the central bank and Powell for the Fed's handling of interest rates.

Trump has had trouble filling recent vacancies on the Fed board, with conservative economist Stephen Moore and the late Herman Cain, a former GOP presidential candidate, withdrawing from consideration after opposition surfaced.