Republicans love Kevin Warsh. But he still has a problem in the Senate.

Republican Sen. Thom Tillis said Friday he will oppose President Donald Trump’s Federal Reserve chair pick until a Justice Department probe into current Fed chief Jerome Powell “is fully and transparently resolved,” a stance that could severely complicate Kevin Warsh’s path to confirmation in the Senate.

The retiring North Carolina lawmaker's vote is needed to advance Warsh’s nomination through the Senate Banking Committee, which oversees the Fed and considers its nominees.

The Powell investigation centers around statements the Fed chief made before Congress about cost overruns at the central bank's Washington headquarters. Tillis has said he will oppose any Fed nominee since the probe became public earlier this month. He said Friday morning on X that Warsh “is a qualified nominee with a deep understanding of monetary policy.”

“However, the Department of Justice continues to pursue a criminal investigation into Chairman Jerome Powell based on committee testimony that no reasonable person could construe as possessing criminal intent,” he wrote. “Protecting the independence of the Federal Reserve from political interference or legal intimidation is non-negotiable.”

Republicans have a 13-11 majority on the Banking panel, meaning that if every Democrat and Tillis oppose Warsh, his nomination would be unable to get out of committee. Asked if the Senate could confirm a Fed pick without Tillis, Majority Leader John Thune said on Thursday: “Uh, probably not.”

Tillis told POLITICO this week that the Justice Department needs to be “completely done” with its investigation before he will consider any new nominees to the institution, meaning the administration needs to either get to a point where they are ready to adjudicate it, “or they can withdraw it because they don’t have sufficient basis for a prosecution,” he said.

And he said he’s ready for a fight with the administration, if need be. “Look, I grew up in a trailer park, and I like a good scrap,” Tillis said. “If these people want to be unprofessional, I’ll match them. If they want to be professional, show some respect for the co-equal branches, then we can resolve this fairly quickly.”

Tillis' objections do not appear to extend beyond the Powell probe, meaning that if the DOJ backed off its investigation, Warsh could likely be confirmed quickly. He said on Bloomberg TV Friday morning he doesn't think Warsh "comes in as more or less going to do the bidding of the administration, which is critically important.”

Other Republicans are lauding the pick. Senate Banking Chair Tim Scott (R-S.C.) said in a statement that Warsh “has deep knowledge of markets and monetary policy that will be essential in this role.” He vowed to lead a “thoughtful, timely confirmation process that carefully examines his vision for focusing the Federal Reserve on its core mission.”

“Federal Reserve independence remains paramount, and I am confident Kevin will work to instill confidence and credibility in the Fed’s monetary policy,” Scott said.

House Financial Services Chair French Hill (R-Ark.) said in a statement that Warsh “brings a clear understanding of the responsibilities of the Fed.”

“He has demonstrated a commitment to fighting inflation and to keeping prices in check for American families and [I] am pleased that President Trump put forward such a qualified nominee,” he said.

Rep. Frank Lucas (R-Okla.), who chairs a House Financial Services task force focused on Fed issues, said on X that Warsh is “the right pick.”

Warsh previously served on the Fed board from 2006 to 2011. He was confirmed by voice vote in the Senate in February 2006, meaning no member objected to his nomination on the floor. But he is certain to face more scrutiny this time around.

The top Democrat on the Senate Banking Committee, Sen. Elizabeth Warren of Massachusetts, said in a statement that Warsh "has apparently passed" Trump's "loyalty test."

"This nomination is the latest step in Trump’s attempt to seize control of the Fed and follows the Trump Administration’s weaponization of the Department of Justice to open criminal investigations into Fed Governor Lisa Cook and sitting Fed Chair Jerome Powell," she said.

Victoria Guida and Dasha Burns contributed to this report.