NEWS ANALYSIS : Ambivalent President Takes Plunge : Russia: Bush seems uncomfortable asking Americans to help pay for the transformation of their Cold War adversary.

He declared it “a defining moment in history,” with stakes equal to Harry S. Truman’s decision to rebuild Europe with the Marshall Plan.

But when President Bush stepped forward at the White House on Wednesday to announce that the United States will join a $24-billion international aid program for Russia, his blueprint came wreathed not in grandeur but in a wary defensiveness.

It was a scene of profound irony, and one that offered new insight into the man who hopes to renew his lease on the Oval Office next fall. No President has relished the role of world leader more than Bush. Yet rarely has a chief executive appeared so discomfited by the demands of statesmanship as has Bush in confronting the need to ask Americans to help pay for the transformation of their Cold War adversary.

The President called the program vital to world peace--but in the next breath defended it as “not a lot of new money.”

In fact, it took impatient allies, insistent advisers--and Democratic challenger Bill Clinton announcing his own Russian aid plan at the very same hour--to get the President to the podium in the first place.

What produced this strange ambivalence and spread confusion in an Administration that once saw foreign policy as its unassailable strong point was Bush’s faltering response to a dilemma that has confronted many presidents in an election year: what to do when history demands a serious decision but the course is politically unpopular.

No matter how unpopular foreign aid may be among voters still struggling through a painful recession, the President cannot duck the issue of what to do about Russia. And he had to take the first step knowing that it may not be the last. Russia’s economic problems are so staggering that today’s relatively modest aid effort may well prove inadequate.

Reflecting the disarray in the Oval Office, once the plan was unveiled, Bush aides spent much of the day struggling to sort out exactly what it contains. “Nobody seems to know,” one official confessed.

For months, when he was under attack by Democrats and by GOP challenger Patrick J. Buchanan for neglecting domestic affairs, Bush gave little more than lip service to the cause of economic reform in Russia. Behind the scenes, Secretary of State James A. Baker III and others pressed for more concrete commitments, but White House and Treasury aides counseled caution.

Then, last month, the political dynamic seemed to turn on its head. Former President Richard M. Nixon, influential Sens. Sam Nunn (D-Ga.) and Richard G. Lugar (R-Ind.) and German Chancellor Helmut Kohl all put public pressure on Bush for more action. Nixon, in a biting memorandum, called the Administration’s efforts “pathetically inadequate” and warned that Bush risked “losing” Russia--that if reformist Russian President Boris N. Yeltsin fails, he could be toppled by a vengeful, authoritarian regime.

At the same time, Buchanan’s challenge faded and Bush aides learned that Clinton planned to attack the President for failing to act on his promises to Moscow.

Bush, under pressure from both sides, then agreed to several elements in the aid program that key aides had originally resisted, including a $1.5-billion U.S. share in an international fund to stabilize Russia’s erratic currency, the ruble. But mindful of voters’ anger over their economic problems, and lopsided polls showing deep-seated resentment of foreign aid, the Administration devised an aid package that requires almost no new appropriations of money by Congress.

Even so, one senior official predicted, “it isn’t going to be easy” to win congressional approval.

Despite the large numbers to which some aides pointed--$24 billion in worldwide aid to Russia, including a $5-billion U.S. share--much of the aid Bush announced was requested months ago. And the vast majority, 87% of the total, is made up of loans, loan guarantees or stabilization funds that are not intended to be spent--not actual cash grants.

That allowed Bush and other officials to emphasize either the large size of the total or the small size of the taxpayers’ actual outlay.

The same paradox was evident in Bush’s main argument for his plan, that allowing the new, democratic Russia to collapse would have far more costly consequences. That was an echo of Truman, who promoted the Marshall Plan by “scaring hell out of the country,” in one adviser’s words.

“If we turn away, if we do not do what we can to help democracy succeed in the lands of the old Soviet Union, our failure to act will carry a far higher price,” Bush warned.

Baker was even more insistent: “Anybody in the government of the United States . . . who says we shouldn’t do anything will be accountable in history if the efforts of democrats and reformers fail in the former Soviet Union,” he said.

But at the same time, the Administration turned aside the question of whether this aid package will be enough, avoiding the issue of whether it expects to ask taxpayers for real money after Election Day.

One senior official, refusing to be quoted by name, circled warily around that question, finally allowing that more aid would have to come eventually--if only to extend economic reforms beyond Russia to the other former Soviet republics.

The aid package won wide praise, including some from critics who had earlier charged Bush with moving too slowly. Even Clinton, after unveiling his own markedly similar proposal, had to give Bush a backhanded compliment:

“I am flattered, I am glad, and I say let’s do some more,” he told reporters in New York.

If Bush sticks with his new commitment, his political dilemma will recur. Aides acknowledge that no one-shot aid program can turn Russia around. In even their “best case” scenarios, fixing the former Soviet economies will remain a major preoccupation for years to come.