Goodling has become a focus of congressional investigators because she played a central role in identifying eight U.S. attorneys who were fired last year. The latest disclosure that she also was involved in the hiring of assistant U.S. attorneys shed new light on her clout at the Justice Department and raised more questions about how the agency has operated under Atty. Gen. Alberto R. Gonzales.

"This is a troubling assertion that, if true, suggests politics infected the most basic operations at the Justice Department," said Rep. John Conyers Jr. (D-Mich.), chairman of the House Judiciary Committee. "This only underscores our commitment to hear directly from Ms. Goodling about her role in this process, and at the Justice Department, to establish who should be held accountable."

The department's investigation, however, could delay the date when lawmakers hear from Goodling. Conyers' panel is trying to win a grant of immunity from prosecution for Goodling, who has said through her lawyer that she would assert her right against self-incrimination if called to testify.

But the Justice Department is unlikely to support immunity while its own probe is pending. The issue of immunity is ultimately decided by a federal judge. Justice Department officials are supposed to weigh in with a recommendation next week.

Department spokesman Dean Boyd declined to provide details about the investigation of Goodling, beyond a three-paragraph statement.

Goodling, the department said, is being investigated in connection with helping review candidates for career positions in certain U.S. attorneys' offices around the country.

The agency declined to say what "prohibited considerations" Goodling might have taken into account, but said that it is against policy and possibly federal law to consider "party affiliation" in deciding whether to hire a career lawyer.

According to people familiar with the investigation, who requested anonymity because the probe is ongoing, Goodling allegedly sought information about party affiliation while vetting applicants for assistant U.S. attorney positions.

Goodling has become a focus of the scandal because she was part of a group of young White House and Justice Department politicos with little or no prosecutorial experience who acted as gatekeepers for U.S. attorney positions. She had also worked in the department's public affairs office, and the office that oversees U.S. attorneys.

Her lawyer, John Dowd, declined to comment Wednesday.

Goodling's activities, the department said, were confined to offices that were headed by interim or acting U.S. attorneys.

The Justice Department has been criticized for using a little-known federal law to appoint interim U.S. attorneys, who do not require Senate confirmation. The practice has triggered allegations from Democrats that the administration is trying to circumvent long-standing checks and balances.

Interim and acting U.S. attorneys do not usually have the authority to hire personnel, the theory being that career prosecutors often outlast their political bosses, and should be selected only when the U.S. attorneys have been Senate-confirmed.

The Justice Department statement Wednesday indicated that the department had granted waivers to a number of those offices so they could hire personnel. But it declined to provide specifics.

Also Wednesday, the Senate Judiciary Committee issued new subpoenas to Gonzales, seeking e-mails in the possession of the department involving presidential advisor Karl Rove.

White House officials said little about the subpoena except to reiterate their previous offer that Rove answer questions behind closed doors without a transcript.

"I know they like to get headlines more than they like to get the facts," said White House spokesman Tony Fratto. "But if there's still any interest in the facts up there, the easiest way is to simply accept our offer to have Karl and others in for interviews."