WASHINGTON — The Justice Department has tapped a federal prosecutor in Chicago to respond to Republican demands for documents on the FBI's handling of the Hillary Clinton email investigation, after President Donald Trump accused officials of "slow walking" their release.

The department is facing mounting pressure from Republicans to fulfill a subpoena by the House Judiciary Committee for more than a million documents as it examines the agency's 2016 investigation into Clinton's private email server. Trump on Saturday slammed the pace of the response, tweeting, "What does the Department of Justice and FBI have to hide?" and says the agencies are "stalling, but for what reason? Not looking good!"

Attorney General Jeff Sessions and FBI Director Christopher Wray responded this weekend. They asked Chicago's U.S. attorney, John Lausch, to ensure document production is fast and that any redactions are necessary. He will also be available to meet with lawmakers.

"Our goal is to assure Congress, the president and the American people that the FBI is going to produce the relevant documents and will do so completely and with integrity and professionalism," Justice Department spokeswoman Sarah Isgur Flores said in a statement.

The Republican chairman of the committee, Rep. Robert Goodlatte of Virginia, is also seeking documents related to Sessions' firing last month of former deputy FBI Director Andrew McCabe. An upcoming inspector general's report is expected to conclude that McCabe had authorized the release of information to the media and was not forthcoming with the watchdog office as it examined the bureau's handling of an investigation into Clinton's emails.

Goodlatte said late last month he had only received a few thousand of the 1.2 million documents he had requested in that investigation, which has long been a source of Republican frustration. The FBI has doubled the number of people working on the request to 54 staffers who are working each day from 8 a.m. to midnight. The Justice Department said it would produce an additional 3,600 pages on Monday.

The addition of Lausch, a Trump appointee, didn't appease House Oversight and Government Reform Chairman Trey Gowdy, who said he was struggling to understand Lausch's role.

"How is injecting someone new into an ongoing review and production process calculated to expedite the process?" he said.