A divided and solemn Congress yesterday granted President Bush the authority to wage war against Iraq and expel its armed forces from Kuwait, the most explicit and sweeping war-making power given the White House in nearly half a century.

In votes that reflected the nation's conflict over how best to resolve the five-month-old military showdown in the Persian Gulf, the Senate voted 52 to 47 to give Bush the authority he sought to enforce a Jan. 15 United Nations deadline for Iraqi withdrawal, and the House followed, 250 to 183.

Those decisions came after both houses of Congress rejected proposals by Democratic leaders to delay war and continue Bush's original strategy of diplomatic isolation and international economic pressure against Iraqi President Saddam Hussein. The House defeated that resolution, 250 to 183. In the Senate the vote was 53 to 46.

In a statement moments after the final votes, Bush said the action "unmistakably demonstrates the United States' commitment to the international demand for a complete and unconditional withdrawal of Iraq from Kuwait. This clear expression of the Congress represents the last, best chance for peace."

Bush told reporters gathered at the White House that the message to Saddam was that he "cannot scorn the Jan. 15th deadline," and said that war, if necessary, would come "sooner rather than later."

Amid the growing sense of momentum in Washington, U.N. Secretary General Javier Perez de Cuellar arrived in Baghdad for a last-ditch peace effort as the United States closed its embassy there and evacuated its remaining diplomatic staff.

Perez de Cuellar, who was met at the airport by Iraqi Foreign Minister Tariq Aziz and was expected to meet with Saddam today, said he had come "as a messenger of peace" but carried no "specific proposal" for a solution to the crisis.

The votes in the House and Senate capped three days of the most intense, solemn and emotional debate seen in the Capitol in many years. In those days, Congress has agonized over the momentous duty delegated to it in Article I of the Constitution, against a backdrop of two huge armies, bristling with modern weaponry, facing each other in the gulf.

Visibly conscious of that weighty constitutional obligation, somber lawmakers in both chambers sat in almost reverent silence yesterday afternoon as they concluded debate and cast what many said were the most troubling and important votes of their careers.

It was, said Sen. William S. Cohen (R-Maine), "an hour of doubt and an hour of destiny."

"There's no vote that is going to stay more in the minds of the people we represent than this vote today," said Sen. Patrick J. Leahy (D-Vt.).

In the Senate, members who normally vote while milling about the chamber sat motionless at their desks until their names were called, then rose to vote in hushed tones. They had done the same when voting for the Intermediate-Range Nuclear Forces Treaty three years ago, applauding when the pact with the Soviet Union was approved. This time there was no applause.

Reflecting the personal agony behind their decisions, many lawmakers recalled their wartime experiences and remarked on the service of relatives and friends among the more than 370,000 U.S. military personnel deployed in Saudi Arabia and the gulf region since Iraqi forces marched into Kuwait on Aug. 2.

The resolution approved yesterday gives Bush congressional authorization to employ military force to enforce the U.N. Security Council resolution authorizing "all necessary means" to compel Iraq to leave Kuwait if it has not voluntarily withdrawn by Jan. 15 -- this Tuesday.

The competing measure, aggressively supported by House Speaker Thomas S. Foley (D-Wash.), Senate Majority Leader George J. Mitchell (D-Maine) and other Democratic leaders, proclaimed that continued reliance on diplomatic initiatives and the international economic embargo was the "wisest course" for the present. That measure did not rule out use of force at a later date, but insisted that Bush return to Congress for specific authorization once he decided to begin a war.

The winning resolution also said that before U.S. troops begin offensive operations, Bush must inform congressional leaders that the United States has used "all appropriate diplomatic and other peaceful means to obtain compliance by Iraq" with the U.N. resolutions. But it requires no further congessional authorization for action.

In the House, 86 Democrats -- including the chairmen of some of the most powerful committees -- supported Bush, and 179 Democrats voted for the alternative. Three Republicans opposed Bush and 164 voted with him. Independent Bernard Sanders (Vt.) opposed the president. Two Democrats did not vote: Morris K. Udall (D-Ariz.), who is hospitalized, and Mervyn M. Dymally (D-Calif.), who is ill.

In the Senate, only two Republicans, Mark O. Hatfield (Ore.) and Charles E. Grassley (Iowa), voted against the president's position, and Hatfield opposed the Democratic proposal as well. Ten Democrats supported it, including Sen. Albert Gore Jr. (Tenn.). Gore, a possible Democratic presidential contender and the last of the group to announce his position, said he saw flaws in both sides of the argument but feared that sanctions alone could not succeed. Sen. Alan Cranston (D-Calif.), undergoing treatment for prostate cancer in California, did not vote.

The substance of yesterday's debates echoed that of the preceding two days. But with the hour of decision approaching, the speeches contained a poignancy that sometimes brought lawmakers to the verge of tears.

They also brought appeals for unity once Congress had spoken. "However you vote," Foley said as he closed debate for the Democrats on the resolution urging continued patience, "let us come together after this vote without recrimination. We are all Americans here -- not Democrats, not Republicans."

"There won't be any nonsense about cutting off funds," said Sen. Ernest F. Hollings (D-S.C.). "No; once we go, we are going together."

Although the resolution approved yesterday was not a formal declaration of war, lawmakers from both sides said it was the functional equivalent. Not since December 1941, when Congress declared war against the Axis powers, have the House and Senate given a president such unequivocal authority to send massive numbers of troops into combat.

"Do not do it under the mistaken notion that you are giving {Bush} just another diplomatic tool," Foley warned members planning to vote to authorize Bush to commit troops. "The president has said again and again that he may use it, and sooner than we realize."

That came in response to the frequent Republican assertion that giving Bush the power to use force against Saddam was the only way to convince the Iraqi leader to withdraw peacefully from Kuwait.

Other supporters of Bush were more explicit about the possible need for force against a despotic Iraqi leader who has vast territorial ambitions and is intent on using weapons of mass destruction to achieve his goals.

"What justifies the threat of force against Saddam Hussein?" asked Rep. Mel Levine (D-Calif.). "It is Saddam Hussein's record of brutal aggression, combined with his nuclear, chemical and biological weapons capability and the threat that that poses to the United States and to the entire world."

"It cannot fairly be said that we have failed to give diplomacy ample opportunity to effect a peaceful solution," said Sen. Warren B. Rudman (R-N.H.). "In light of Iraq's intransigence, it would appear more accurate to say that diplomacy has failed to provide the desired end."

Democrats in turn argued that Bush's original policy of employing an international economic embargo and diplomatic pressure would eventually prevail if the United States exhibited sufficient patience. The alternative, they said, was an unpredictable and violent clash that might shatter the fragile international coalition, escalate into a region-wide war involving Israel and poison U.S. relations with nations in the troubled region for years.

"Iraq is isolated and suffering from the embargo, and time is on our side," said Senate Armed Services Committee Chairman Sam Nunn (D-Ga.), who has often supported Republican administration defense policies but emerged as a key opponent of Bush on the use of force at this time. "In short, we are playing a winning hand. I see no compelling reason to rush to military action."

Even stronger in his denunciation of war as a solution to the gulf crisis was Republican Hatfield.

The Pentagon is trying to "give us the impression that war will come in a tidy little package," even to the point of referring to body bags as "human remains pouches," he said. "If we are this divided now, think about how divided we will be when the shooting starts and when our young people begin coming home in those 'human remains pouches' that aren't so neat and tidy after all." The nation does not want this war, Hatfield added. "We have the firepower, but we do not have the will."

Shortly after the Senate vote, Dole invited Iraqi Ambassador Mohamed Mashat to his office to meet with 10 senators of both parties who supported the president's position. The ambassador listened gravely as the senators described their vote as a last-minute bid to avoid war through withdrawal of Iraqi forces from Kuwait and said he would pass the message on to Baghdad, according to a Dole aide.

During the meeting, Bush called Dole to thank him for his role in passing the resolution and also talked briefly to Democratic senators there.

Even though the gravity of the debate drove out most of the normal partisan rancor, there was some finger-pointing from both sides.

"The president says he's angry and impatient, but, God bless him, so are all of us. But is that a reason to send a whole generation to war?" asked Sen. Joseph R. Biden Jr. (D-Del.), a member of the Foreign Relations Committee. "We'll finish what you started, Mr. President . . . but, for God's sake, don't start unless you feel it is of vital interest. I do not," he said.

Turning his fire on his colleagues, rather than the president, Dole said that Congress should have acted earlier and should not try to intervene "now, at the 11th hour, having been AWOL for three or four months, and try to change the direction of the policy that President Bush has so patiently and successfully put together."

But for lawmakers from both sides, particularly those who had seen combat or had relatives now serving in the armed forces or had sharp memories of the divisiveness of Vietnam, this was above all an intensely personal debate.

"I am not unlike many of my constituents who have family serving in the gulf," said Rep. Jerry Lewis (R-Calif.), who supported the president. "My nephew Erich, who commands a Blackhawk helicopter crew, is among the thousands of young men and women on the front lines in the Saudi desert. Thoughts of him weigh heavily on my mind."

On the other side, Rep. Thomas J. Downey (D-N.Y.) remembered the day in 1983 when he attended two funerals in his Long Island district, one for a Navy SEAL killed in Grenada, the other for a Marine who died in the Beirut barracks bombing.

"There was nothing I could say or do that made any difference," said Downey. "Those parents were inconsolable."

Staff writers John E. Yang and Dan Balz in Washington, and Tod Robberson in Baghdad, contributed to this report.