NEWS ANALYSIS : President Faces the Withering Test of 2 Major Crises at the Same Time : White House: Hussein has called his military hand, and Gorbachev is proving to be a liability.

For most of his presidency, George Bush has made the shining promise of a “new world order” the centerpiece of his claim to international leadership. Today, that promise stands in mortal danger, facing the withering test of two major crises at once.

In the Persian Gulf, Iraq’s Saddam Hussein has called the President’s military hand, demanding trial by combat after five months of international pressure. In the Soviet Union, Mikhail S. Gorbachev, the reformer whom Bush embraced as a worthy partner in remaking the world, is presiding instead over a violent crackdown in the Baltic states.

In the center of the storm--a place of eerie quiet but crushing pressure--stand Bush and his lieutenants, who know only too well that the decisions they make over the coming few days will shape not only their own political destinies but the international order for the rest of this decade and perhaps beyond.

The strain is visible in the faces of the President and his secretary of state, James A. Baker III, who briefed members of Congress in the White House Cabinet Room on Monday after Baker’s return from a nine-day, 11-country journey to prepare the way for war. Bush was tired and grim and Baker somber and hoarse, the lawmakers said.

The strain is visible, too, in the fevered schedules of the President’s top aides, who--already working long hours on the Persian Gulf showdown--have been forced to add new rounds of meetings on the upheaval in the Soviet Union.

Presidents have faced multiple crises before: in 1956, when Moscow sent tanks into Hungary even as a war raged over the Suez Canal; in 1973, when another Middle East war touched off a nuclear alert while armies battled in Vietnam; in 1983, when the United States invaded Grenada as American Marines were collecting their dead in Beirut.

But rarely has a President confronted two problems that struck so close to the heart of the national interest, or that so directly threatened the pillars of a new, still-unfinished foreign policy structure.

As recently as September, Bush could speak of the Persian Gulf crisis as “a rare opportunity” to forge new bonds with old enemies. Flushed with the success of his Helsinki summit with Gorbachev, who pledged to put the Soviet Union at America’s side, Bush proclaimed it “a unique and extraordinary moment.”

“Out of these troubled times,” he said, “. . . a new world order can emerge: a new era, freer from the threat of terror, stronger in pursuit of justice and more secure in the quest for peace.”

There was no such soaring language on Monday when Bush, after his closed-door meeting with congressional leaders, signed the joint resolution of Congress authorizing him to go to war.

“This resolution provides the best hope for peace,” said a brief written statement issued by the White House. “Iraq’s ongoing aggression against . . . Kuwait shall not stand.”

The President’s mood, and that of his visitors, seemed tinged with more than just the growing certainty that war will come. It was brought low as well by the Soviet Union’s apparent turn away from the promise of democracy toward old habits of repression; and by the growing realization that even a successful war in the Middle East could well bring years of instability and danger in its wake.

To some Administration officials, the sudden reversal in the Soviet Union was every bit as sobering as the slide toward war, because the idea of a “partnership” with Gorbachev had become so central to the foreign policy Bush and Baker were trying to build.

The “senior Administration official” who travels anonymously on Baker’s airplane seemed especially bitter as he told reporters of the consequences.

“We’re not going to be able to move this U.S.-Soviet relationship forward in a cooperative way, certainly not on the path of partnership, unless there are shared principles and shared values. Shared principles and shared values means you don’t use tanks against peaceful demonstrators,” he said.

“There are still, in my opinion, areas where it is to the mutual advantage of the two countries to continue to try and work things out,” he added. But it was a long way from the vision of two superpowers in “partnership” that Baker and Bush had earlier embraced.

“They probably went too far on that,” Cold War veteran Helmut Sonnenfeldt said of the Bush Administration’s hopes for working in tandem with Moscow. Sonnenfeldt was a senior State Department official during the detente years of the Nixon and Ford administrations. “Partnership implies a general convergence of values and habits and confidence in each other. That’s going to break down. The Soviets may simply not be capable of being a good partner because of the chaos and economic weakness there.”

The chill in U.S. relations with the Soviet Union is not confined to the issue of the Baltics, he noted. The Soviet military has also tried to walk away from its commitments to destroy thousands of tanks and combat aircraft as part of the agreement on conventional forces in Europe, one of the concrete steps in ending the Cold War.

In at least one sense, the Soviet and gulf crises are connected: Bush was relying on his new alliance with Moscow as a key link in the international coalition against Iraq, but a less-benign Kremlin could be a less-reliable partner in the gulf as well.

“There’s much more of a question mark now over Soviet cooperation in the gulf because of the question of who’s in charge in Moscow and how far they are prepared to go,” Sonnenfeldt observed.

The strains of the gulf crisis have exposed differences with other would-be allies: with Japan and Germany, the economic powerhouses of the “new world order,” which have drawn unusual private bitterness from some U.S. officials for their slow and seemingly grudging financial support for the gulf coalition; and with France, which launched a last-minute peace proposal on Monday that drew an instant, almost disdainful American rebuff.

Also, as the crisis has continued, U.S. intelligence analysts and experts outside the government began producing a stream of projections outlining the problems that could follow even a swift and triumphant military operation in the gulf: terrorism across the Muslim world, the governance of a defeated Iraq, the construction of a new security balance in the gulf.

“If this war starts, the problems aren’t going to be confined to the immediate area,” warned Phebe Marr, a Middle East expert at the Pentagon’s National Defense University.

And those assessments assume that the United States would win a war in a matter of a few months. If Iraq’s armies turn out to be more tenacious than U.S. strategists expect, the problems would, of course, be worse.

“If this thing turns bad--if we get into a Vietnam situation, a long war between Arabs and Americans--it could be a disaster,” warned David P. Calleo of Johns Hopkins University’s School of Advanced International Studies here. “The Soviets might slowly disengage from the coalition. The Europeans would get sick of both us and of the Middle East--and begin to disengage from American diplomacy. In the long run, we could be weakened and alone.”

Calleo admitted that such a scenario is probably unduly pessimistic. “The real picture is more a matter of trends, but even trends in that direction aren’t very good,” he said.

Not everyone is so downbeat.

“We still have a new world order, if only because the Soviet Union has withdrawn from Eastern Europe and the Cold War is over,” said Michael Mandelbaum of the Council on Foreign Relations in New York.

“The Soviet Union isn’t remotely a military threat to Europe,” he noted. “There are freely elected governments in Eastern Europe.”

Still, Mandelbaum acknowledged, the new world order has turned out to be much more limited--and more difficult to give birth to--than it was once cracked up to be.

“It may not be quite as snug and rosy and cost-free and painless as we had expected,” he said.