Moore co-founded, in 1999, and for five years led the conservative Club for Growth, which helps fund GOP primary challengers to incumbent moderates in the House and Senate. The group backs limited government, lower income tax rates, less red tape, and also an end to government efforts to address climate change.

When he was head of the group, he took aim at senators in the GOP majority under President George W. Bush. He tried unsuccessfully to replace moderate Republican Senator Arlen Specter of Pennsylvania with Republican primary challenger Pat Toomey, who lost by two percentage points and then went on the replace Moore as president of the Club for Growth. Toomey was elected to the Senate in 2010.

The group also ran ads in the home states of GOP senators George Voinovich of Ohio and Olympia Snowe of Maine, saying they were resisting a portion of Bush’s tax cuts. Both have since left the Senate.

Fed Vacancy

The Fed vacancy doesn’t need to be filled right away and Moore’s nomination could just languish if GOP Senate leaders see that the Trump ally is not getting strong backing, said Sarah Binder, a political science professor at George Washington University.

For much of last year, the seven-seat board had only three members, causing Fed officials to appeal repeatedly to lawmakers to approve new nominees. That pressure has subsided since the confirmations late last year of Vice Chairman Richard Clarida and Governor Michelle Bowman.

“The question is, does” Senator Majority Leader Mitch McConnell “take the time to put the sixth wheel onto the Fed,” Binder said, adding that Trump nominees to other jobs could be a greater priority. “Part of that is whether he gets any negative signals from his colleagues.”

In addition to picking fights with lawmakers, Moore, an economic adviser on Trump’s 2016 campaign has criticized Powell. In a December interview with the Wall Street Journal, he called Powell “totally incompetent’’ after the board raised interest rates. On Monday he dialed that back, telling the Journal that he was harsh in his assessment “and I wish I hadn’t been.’’

Moore is Trump’s sixth nomination to the nation’s monetary authority, a board typically populated with trained economists, bank regulators and financial-industry executives.

Greg Mankiw, a Harvard professor who was chairman of the White House Council of Economic Advisers under George W. Bush, on Friday called on senators to reject him. Writing in a blog post, Mankiw said that Moore “does not have the intellectual gravitas for this important job.”