WASHINGTON (AP) — The Justice Department has ended its investigation into Federal Reserve chair Jerome Powell, clearing a major roadblock to the confirmation of Kevin Warsh as his successor.

U.S. Attorney for the District of Columbia Jeanine Pirro said on X Friday that her office was ending its probe into the Fed’s extensive building renovations because the Fed’s inspector general would scrutinize them instead.

The move could lead to a swift confirmation vote by the Senate for Warsh, a former top Fed official whom President Donald Trump, a Republican, nominated in January to replace Powell. Powell’s term as chair ends May 15. Sen. Thom Tillis, a North Carolina Republican, had said he would oppose Warsh until the investigation was resolved, effectively blocking his confirmation.

Republicans praised Warsh during a Tuesday hearing as Democrats questioned his independence from Trump, the lack of transparency around some of his financial holdings, and what they said was his flip-flopping on interest rates. Still, Trump’s previous appointment to the Fed’s board of governors, Stephen Miran, was approved by the full Senate just 13 days after his nomination.

Pirro’s investigation focused on a $2.5 billion building renovation that Trump criticized sharply last year for its cost overruns. Trump visited the building last July and on camera presented to Powell an inflated cost estimate, which Powell corrected as the two stood at the construction site in hard hats.

Earlier estimates for the project had put the cost at $1.9 billion. The investigation also covered Powell’s brief testimony about the renovation before the Senate Banking Committee last June.

Pirro also said on X, “I will not hesitate to restart a criminal investigation should the facts warrant doing so.” Powell has previously asked the Fed’s independent inspector general to investigate the cost overruns.

The probe was among several undertaken by the Justice Department into Trump’s perceived adversaries. For months it had failed to gain traction as prosecutors struggled to articulate a basis to suspect criminal conduct. Other efforts by the department to prosecute Trump’s adversaries have also been unsuccessful.

A prosecutor handling the Powell case conceded at a closed-door court hearing in March that the government hadn’t found any evidence of a crime, and a judge subsequently quashed subpoenas issued to the Federal Reserve.