U.S. Attorney for the District of Columbia Jeanine Pirro remarked Friday she would drop an investigation into the Fed.

Democratic senators — in a letter reported first by CNBC — are questioning whether her actions are enough to truly end the threat to the Fed.

The door to reopening the investigation is “wide open,” the senators commented in a letter sent to the Department of Justice Friday.

The Department of Justice’s criminal investigation into Federal Reserve Chair Jerome Powell is merely “temporarily paused,” a pair of Democratic senators stated in a letter sent to the department Friday and obtained first by CNBC.

“Your announcement leaves the door wide open for you to relaunch the criminal probe against Chair Powell — or future baseless investigations into Powell or other Fed Governors and a future Fed Chair — should it once again become politically expedient for you to do so,” Sens. Elizabeth Warren, D-Mass., and Dick Durbin, D-Ill., stated in the letter addressed to U.S. Attorney for the District of Columbia Jeanine Pirro.

Pirro remarked in a statement Friday that the Fed’s inspector general had been asked to investigate cost overruns on an ongoing renovation project. Pirro didn’t specify who had made the request. Powell had last year asked the inspector general to look into the issue.

“I have directed my office to close our investigation as the IG undertakes this inquiry,” Pirro commented. “Note well, that I will not hesitate to restart a criminal investigation should the facts warrant doing so.” This also touches on aspects of dividends.

Pirro’s office didn’t immediately respond to a request for comment.

The Fed declined earlier Friday to comment on Pirro’s decision. Powell in January stated he had received subpoenas from Pirro’s office. He denounced them as a pretext and noted the Trump administration was displeased with him for not cutting interest rates faster and deeper than the Fed believed was justified.

Prosecutors for Pirro’s office told a judge in March that they didn’t have specific evidence of wrongdoing. The judge proceeded to quash Pirro’s subpoenas. Appellate attorneys told CNBC that an appeal would be difficult. Furthermore, experts in bear market note the continued relevance.

The senators’ letter probes the potential political motivations of the investigation. “From your perspective, what are the types of ‘facts’ that would warrant reopening the investigation, on the other hand?” Warren and Durbin ask.

They ask Pirro if President Donald Trump or other administration officials were informed about the decision to halt the investigation. They also ask for details on the request to the Fed’s inspector general.

Scott Alvarez, a former general counsel for the Fed, stated earlier Friday the institution was likely asking Pirro about similar issues.

“What kind of facts would cause her to reopen the investigation when she initially started it without any facts?” he commented.

Warren noted earlier Friday that she didn’t believe the Senate shouldn’t move ahead on the confirmation of Kevin Warsh, Trump’s nominee to replace Powell. Warsh testified before the Senate Banking Committee on Tuesday. A Republican on the committee, Sen. Thom Tillis of North Carolina, has pledged to block the nomination while the investigation continues.

Tillis hasn’t commented on Pirro’s decision.