Senate Democrats called for a special counsel to investigate whether Attorney General Alberto Gonzales lied under oath and subpoenaed top presidential aide Karl Rove Thursday in a widening probe into the dismissal of U.S. prosecutors.

Bush administration officials have consistently denied any wrongdoing in connection with the firing of the prosecutors, who were let go last winter. Democrats charge the dismissals were politically motivated.

Gonzales is at the center of the U.S. attorney controversy, but the call for a perjury probe involved alleged conflicts between testimony he gave the Judiciary Committee last year and this week. The issue revolves around whether there was internal administration dissent over the president's warrantless wiretapping program.

Democrats and some Republicans have called for Gonzales to resign as head of the Justice Department and chief U.S. law enforcement officer. President Bush has repeatedly expressed support for his longtime friend.

As for the firing of the prosecutors, e-mails released by the Justice Department show Gonzales' aides conferred with Rove on the matter.

"It has become apparent that the attorney general has provided at a minimum half-truths and misleading statements," four members of the Senate Judiciary Committee wrote in a letter to Solicitor General Paul Clement, the U.S. government's top lawyer.

They dispatched the letter shortly before Sen. Patrick Leahy, the Democratic committee chairman, announced the subpoena of Rove, the president's top political strategist.

"We have now reached a point where the accumulated evidence shows that political considerations factored into the unprecedented firing of at least nine United States Attorneys last year," said Leahy.

Leahy also said he was issuing a subpoena for J. Scott Jennings, a White House political aide.

"For over four months, I have exhausted every avenue seeking the voluntary cooperation of Karl Rove and J. Scott Jennings, but to no avail," the lawmaker said. "They and the White House have stonewalled every request. Indeed, the White House is choosing to withhold documents and is instructing witnesses who are former officials to refuse to answer questions and provide