Members of Congress closed ranks last night to back the men and women waging a war that many lawmakers had sought to avert four days earlier.

Even those who had strongly opposed giving President Bush the authorization he sought to launch last night's assault expressed their support for the soldiers, sailors, Marines and airmen engaged in Operation Desert Storm.

"We don't want anyone in harm's way to think there is a lack of support in Congress -- nor will there be," said Sen. John Glenn (D-Ohio).

"We must now stand united in support of our armed forces in the gulf who have embraced the duty and burden of conducting the war," House Speaker Thomas S. Foley (D-Wash.) said in a statement. "We must now pray for a conflict that ends quickly, decisively and with a minimum loss of life."

Sen. David L. Boren (D-Okla.), chairman of the Senate Select Committee on Intelligence, predicted "unanimous support {in Congress} for our troops and the resources necessary to prevail. . . . You'll see Congress playing the role of supporting player."

Some of those who on Saturday had voted against the congressional resolution authorizing the use of force continued to express reservations. "It's not a good feeling," said Rep. Silvio O. Conte (R-Mass.), one of three House Republicans who opposed Bush. "But at a time like this, you've got to rally behind your troops. Anything else would be dishonorable. It's a sad day."

Describing the congressional mood, Senate Minority Whip Alan K. Simpson (R-Wyo.) said: "I don't think there was any sense of glee or satisfaction {in Saturday's vote} and I think the same is true today."

At least one lawmaker was vocal in his dissent. Rep. Ronald V. Dellums (D-Calif.) declared himself to be "outraged" and called war with Iraq "an inestimable tragedy, one for which it will take us a lifetime to atone."

But generally members of Congress praised Bush, Defense Secretary Richard B. Cheney and Gen. Colin L. Powell, chairman of the Joint Chiefs of Staff, for using substantial force in the initial attack and predicted a quick, decisive victory.

"I believe we will prevail in a matter of days or weeks," said Senate Armed Services Committee Chairman Sam Nunn (D-Ga.), who had been a proponent of giving economic sanctions more time to work. "Saddam Hussein has made a tragic miscalculation."

Senate Minority Leader Robert J. Dole (R-Kan.) praised Bush for speaking "eloquently . . . of our national purpose in the gulf." But Glenn found Bush's nationwide television address wanting. "I'm sure the American people will unite behind the president, but it still has to be explained . . . why we are there," he said.

Rep. Lee H. Hamilton (D-Ind.) warned that backing for Bush's Desert Storm operation would last "provided he wins that war rather quickly." If it becomes prolonged, "there will be some real political difficulty sustaining that political support," he said.

The Senate is expected to approve today a bipartisan measure supporting the action. Last night, House leaders had not decided when to return for a full legislative session.

For most of the day, lawmakers and their aides on Capitol Hill watched and waited with a mounting sense of apprehension. Office television sets were tuned to CNN to keep up with whatever developments there were. By late afternoon, rumors were rife: Either Bush was on his way to the Capitol to speak with leaders or the leaders were on their way to the White House. Neither version proved to be true.

By late afternoon the ritual of notification had begun. Bush tracked down Foley at 5:30 p.m. at Brooks Brothers in downtown Washington, where he was shopping for shirts. The House speaker returned to his second-floor Capitol office so he could call the president back on a telephone that had been screened for wiretaps.

House Minority Leader Robert H. Michel (R-Ill.) had been called shortly before Foley, and Bush spoke with Senate Majority Leader George J. Mitchell (D-Maine) afterward.

Sen. Robert C. Byrd (D-W.Va.) was reached at about 6 p.m. "My Bible tells me that our heavenly father . . . will reward us," Byrd recalled telling the president. "I pray for you every night."

As news of the attack spread, security at the Capitol, already tight, was further increased. Squads of Capitol police, clad in slate-gray jumpsuits and many with dogs in tow, guarded the building.

Robert M. Gates, Bush's deputy national security adviser, went to Capitol Hill with the written certification required by the congressional resolution that diplomatic efforts to end Iraqi occupation of Kuwait had failed. He met with Mitchell and Dole and then headed through the Rotunda to Foley's office.

There, he found House Majority Leader Richard A. Gephardt (D-Mo.), who had been summoned by Foley. In another room in Foley's suite, House Democratic leadership aides clustered around a television set, watching initial reports of the attack on Iraq. Hunkering down for a long night, they sent out for pizza.

After speaking with Bush, Michel sat alone in his office, behind closed doors, before returning to a meeting with staff. He briefly returned to the solitude of his office before walking to Dole's office to watch the news on television.

"We all regret that this military action had to begin . . . but clearly Saddam's decision to ignore the U.N. resolutions . . . has led us here," Michel said in a statement. "We now pray fervently for the protection of our men and women in uniform. . . . We hope that their superior character and performance will bring Saddam to his knees just as quickly and assuredly as possible." Staff writers Helen Dewar, Tom Kenworthy and Don Phillips contributed to this report.