WASHINGTON, April 12 —The White House said today that it might be missing e-mails relating to the firing of eight United States attorneys, as lawmakers on Capitol Hill gave themselves the authority to subpoena more government documents and testimony linked to the controversy.

“It can’t be ruled out,” Scott Stanzel, the deputy White House press secretary, told reporters this morning when asked if some of the missing e-mails included those related to the dismissals.

At the same time, the Senate Judiciary Committee empowered its chairman, Senator Patrick J. Leahy, to serve subpoenas for documents that may explain the firings, and to compel testimony from Scott Jennings, a deputy political director in the White House whose e-mails, on a Republican National Committee account, have set off a separate inquiry into the use of political e-mail accounts for official government business.

On the Senate floor, Mr. Leahy was skeptical that the e-mails are indeed missing. “You can’t erase e-mails, not today,” he said. “They’ve gone through too many servers.”