An FBI agent involved in the Hunter Biden probe said the prosecutor leading it sought, but was denied, help from a key fellow U.S. attorney.

The lack of cooperation did not prevent charges from being brought against the president’s son, the agent told congressional investigators. But it did make the prosecutor’s job harder.

The testimony, delivered behind closed doors, is consistent in part with an IRS whistleblower’s description of the probe and comes at a critical juncture in the investigations into the Biden family. Republicans have pointed to that whistleblower description when making the case for opening an impeachment inquiry into President Joe Biden.

But the agent also said she did not recall another key part of the whistleblower’s allegations that Republicans have focused on: that David Weiss, the Trump-appointed U.S. attorney for Delaware, said he didn’t have final authority to charge the president’s son.

During her testimony to Congress, the agent indicated that the U.S. attorney in California — appointed by President Joe Biden — declined to partner with Weiss in pursuing tax charges against the president’s son.

“I remember learning at some point in the investigation that Mr. Weiss would have to go through his other processes because the U.S. attorney’s offices had, I guess, in that sense, using that terminology, wasn’t going to partner,” she said.

Asked if she recalled learning that Martin Estrada, the U.S. attorney for the Central District of California, specifically decided not to bring tax charges against Hunter Biden, the agent replied: “I understand that, yes, that a decision had been made that the Central District of California wasn’t going to, I guess — my understanding is that they weren’t going to bring the case on their own.”

She added that the lack of cooperation would not have ultimately prevented Weiss from bringing tax charges against Hunter Biden.

“He would still have the authority to do so,” she said. “It’s just that now he would do it differently.”

The agent’s testimony was made as part of a voluntary interview she gave to the House Judiciary Committee. POLITICO reviewed the transcript of that interview. We are not publishing the agent’s name because a person familiar with the Congressional probe said she handles sensitive work for the FBI. The agent sat for the interview with the judiciary committee with the Justice Department’s blessing, and was accompanied by lawyers for the Department and the FBI.

The testimony adds yet another element in a legal and political saga that has spanned years and sparked House Speaker Kevin McCarthy’s announcement of an impeachment inquiry of the president.

Hill Republicans investigating the Biden family have been particularly focused on the extent to which Weiss faced headwinds from other Justice Department officials.

Gary Shapley, an IRS official-turned-whistleblower, has said investigators scrutinizing the first son faced unusual hurdles. He testified that U.S. attorneys in California and D.C. refused to partner with Weiss. He has also said that Weiss said in a meeting on Oct. 7, 2022 that he was “not the deciding person” in the probe.

Shapley’s contemporaneous notes detail that last comment. But two other meeting participants have told lawmakers they do not remember it. Both Weiss and Attorney General Merrick Garland have long defended the integrity of the probe and Weiss’ authority to bring charges where he deemed necessary.

Empower Oversight, a nonprofit helping Gary Shapley, pictured, said in a statement that David Weiss failed to do his job properly.