WASHINGTON - The top Republican on the Senate committee investigating Attorney General Alberto Gonzales said Sunday he believes Gonzales could resign before a no-confidence vote sought this week by Senate Democrats.

In a further sign of his eroding support within the GOP, Gonzales failed to draw a public statement of support from Senate Republican leader Mitch McConnell. Asked whether Gonzales effectively can lead the Justice Department, McConnell said "that's for the president to decide." The senator suggested there may be several resolutions introduced to dilute a no-confidence vote.

"In the Senate, nobody gets a clear shot," said McConnell, R-Ky.

Yet Pennsylvania Sen. Arlen Specter, the ranking Republican on the Senate Judiciary Committee, said he believed a "sizable number" of GOP lawmakers would join Democrats in expressing their lack of confidence in the attorney general.

"I have a sense that before the vote is taken, that Attorney General Gonzales may step down," Specter said.

Five Republicans have urged Gonzales to resign over his firing of federal prosecutors, while several other Republicans have expressed criticism of his actions.

"Votes of no confidence are very rare," Specter said. "Historically, that is something which Attorney General Gonzales would like to avoid. I think that if and when he sees that coming, he would prefer to avoid that kind of a historical black mark."

White House spokesman Tony Fratto said Sunday that Gonzales would not be affected by a potential vote of no confidence. "As for no-confidence votes, maybe senators need a refresher course on American civics," Fratto said while with Bush at his Texas ranch. "I think you find no-confidence votes in parliamentary systems, not the American system of government."

Specter long has made it clear he believed the Justice Department no longer functioned well because of Gonzales' handling of the prosecutor firings and that as a result Gonzales would step down.

But Specter's and McConnell's comments Sunday raised the pressure on Gonzales and Bush, who has indicated Gonzales would not be leaving anytime soon.

Democratic Sens. Chuck Schumer of New York and Dianne Feinstein of California said they will seek a vote on a nonbinding resolution as early as this week to express what senators of both parties have said for weeks: that Gonzales has become too weakened to run the department.

Department spokesman Brian Roehrkasse said Gonzales was concentrating on doing his job. "As we work to ensure Congress has all the information it needs on this matter, the attorney general remains focused on the important work that the American people expect him to do," Roehrkasse said Sunday.

A no-confidence vote, though symbolic, probably would create trouble for Gonzales. Any attorney general needs to work with Congress on legislation, as well as nominees who require Senate confirmation. Gonzales would need to confirm a new deputy attorney general because his current one, Paul McNulty, is leaving over the firings of federal prosecutors.

Gonzales will be in Washington today and part of Tuesday before heading to Europe, visiting counterparts in Hungary and Switzerland and then joining a conference of leading industrial nations Thursday in Germany. He will be back in Washington on Friday -- before the Memorial Day weekend and a congressional vacation.

Specter and other senators said they were particularly troubled by testimony last week that Gonzales, when he was Bush's White House counsel, pressured then-Attorney General John Ashcroft to certify the legality of Bush's controversial eavesdropping program while Ashcroft was in intensive care.