The Justice Department revealed Tuesday that law enforcement officials running Ukraine-related investigations must seek approval before expanding their inquiries — a move that could have implications for Rudolph W. Giuliani, as President Trump’s personal attorney pushes for scrutiny of the president’s political foes while facing a federal probe into his own conduct.

The directive from Deputy Attorney General Jeffrey A. Rosen was disclosed in a response to Rep. Jerrold Nadler (D-N.Y.) after the House Judiciary Committee chairman demanded clarity on how the Justice Department is reviewing information from Giuliani, who has urged law enforcement to investigate former vice president Joe Biden and his son for their dealings in Ukraine.

Assistant Attorney General Stephen E. Boyd wrote to Nadler that the department had tapped two U.S. attorneys to assist in the process — Scott Brady in Pittsburgh to receive and assess new information, and Richard Donoghue in Brooklyn to help coordinate personnel throughout the Justice Department involved in Giuliani’s case and others with a focus on Ukraine. An accompanying internal memo, circulated by Rosen in January, says that he and Donoghue must approve expansions of any inquiries.

Such a move could be viewed as putting another layer of approval in place if prosecutors wanted to widen their Giuliani probe, although Rosen wrote in his memo that the aim was to “avoid duplication of efforts.”

In his letter to Nadler, Boyd defended the moves as normal and said that they do not give anyone special entry to the department.

“The Department regularly assigns U.S. Attorneys to coordinate or focus on certain matters,” Boyd wrote. “Nor do these procedures grant any individual unique access to the Department. Indeed, any member of the public who has relevant information may contact the Department and make use of its intake process for Ukraine-related matters.”

Attorney General William P. Barr faced criticism from congressional Democrats and former Justice Department officials when he acknowledged last week having created an “intake process in the field” to accept Giuliani’s information, which seems designed to damage Biden’s political prospects as he seeks the Democratic nomination for president. Barr said at that time that the department had an “obligation to have an open door to anybody who wishes to provide us information that they think is relevant.”

Taking information from Giuliani is particularly fraught for the department because the president’s personal lawyer is under investigation by federal prosecutors in Manhattan in a case that has led to campaign finance charges against two of Giuliani’s associates, Lev Parnas and Igor Fruman. The pair helped Giuliani try to conduct investigations in Ukraine and lobbied for the ouster of Marie Yovanovitch, the former U.S. ambassador to Ukraine. Prosecutors have in recent weeks contacted witnesses and sought to collect additional documents in that case.

Separately, federal prosecutors in Chicago have a long-standing case against a Ukrainian gas tycoon accused of bribery, Dmitry Firtash, who they suspect of having significant ties to Parnas and Fruman. And federal prosecutors in Cleveland have been investigating Ihor Kolomoisky, a Ukrainian oligarch, for possible financial crimes. He has sparred publicly with Giuliani.

Trump and Giuliani have pressed the Ukrainians to investigate Biden and his son Hunter, who worked on the board of a Ukrainian energy company while his father oversaw the Obama administration’s Ukraine policy. In a phone call in July, Trump personally appealed to his presidential counterpart in Ukraine, Volodymyr Zelensky, to work with Barr on the matter. That call, coupled with Giuliani’s efforts, formed the basis of House Democrats’ decision to impeach the president.

Kerri Kupec, a spokeswoman for Barr, said in a September statement issued after the White House disclosed a rough transcript of Trump’s call with the Ukrainian president that Trump had not spoken with Barr “about having Ukraine investigate anything relating to former Vice President Biden or his son.”

“The President has not asked the Attorney General to contact Ukraine — on this or any other matter,” Kupec said. “The Attorney General has not communicated with Ukraine — on this or any other subject.”

Boyd wrote in the letter to Nadler that the September statement “remains accurate” and that Barr “has not discussed matters relating to Ukraine with Rudolph Giuliani.”

The Justice Department in the Trump administration has turned repeatedly to U.S. attorneys outside Washington to handle politically explosive cases, and current and former officials have said they worry the moves are meant to help Trump politically.

Two top federal prosecutors — John Durham, the U.S. attorney in Connecticut, and Jeff Jensen, the U.S. attorney in St. Louis — have been tasked with exploring aspects of the FBI’s 2016 investigation into whether the Trump campaign coordinated with Russia to influence the election. Durham is examining the probe’s origins; Jensen is reviewing, among other things, the case that prosecutors on that investigation made against former Trump national security adviser Michael Flynn for lying to the FBI.

Another federal prosecutor, U.S. Attorney John Huber in Utah, was tasked by then-Attorney General Jeff Sessions to investigate old corruption allegations against Hillary Clinton, the former secretary of state and Trump’s opponent in the 2016 campaign. His inquiry, though, ultimately went nowhere.