When Nikita Khrushchev met for the first time with John F. Kennedy in 1961 at the Vienna summit, the Soviet leader claimed that the Kremlin had cast the deciding ballot in Kennedy's slim electoral victory over Richard Nixon.

His reasoning was this: by delaying the release of U2 spy-plane pilot Francis Gary Powers until after the election, Khrushchev had denied Nixon a diplomatic victory and the opportunity to claim he knew how to deal with the Soviets. The ploy, Khrushchev told Kennedy, must have cost Nixon a half million votes--far more than the margin of victory.

U.S. leaders traditionally have held fewer illusions about the sway they hold over the selection of leaders inside the Kremlin. Nonetheless, as the struggle among Kremlin insiders to succeed the ailing 75-year-old Leonid Brezhnev begins, U.S. policy-makers and Kremlinologists are debating how to react to what many see as a rare chance to influence Soviet actions and ambitions.

In his arms control speech last week ago at Eureka College, President Reagan said, "We are approaching an extremely important phase in East-West relations as the current Soviet leadership is succeeded by a new generation." Secretary of State Alexander M. Haig Jr. in a recent speech called the succession a "historic opportunity" for the West to influence Soviet actions by making clear to the Kremlin's new men "the benefits of greater restraint."

Despite those assessments, analysts in and out of government say the Reagan administration, torn by deep internal disputes that are both ideological and personal, has only begun to take the first, tentative steps toward a coherent and consistent policy on Soviet succession.

Most Sovietologists believe that leadership changes in Moscow--as in Washington--are the result of internal politics generally not subject to influence by outside forces. Still, there have been historic moments when succession crises and foreign policy have touched. Some analysts believe the West squandered a golden opportunity when John Foster Dulles rejected Winston Churchill's advice to offer to the new Kremlin leadership a fresh relationship following Stalin's death in 1953. Others hold that the turning point in detente came in 1973, when Brezhnev and his advisers during their visit to the United States came to realize that Watergate had fundamentally crippled Richard Nixon's presidency and his policies. The Soviet military buildup soon followed.

Once again, the administration and the small group of Kremlinologists whose analyses and debates have become a Washington cottage industry are attempting to draw a fix on the succession, its probable winners and losers and the policy issues that will play a role. Haig recently called together the country's most prominent Sovietologists for an off-the-record dinner at State. One of the themes that emerged, said one participant, was not to trust anyone who claimed to be able to predict who would win and where the winner would lead the Soviet Union. Even the CIA has urged caution.

In a recent 45-page, top-secret analysis presented to the president, intelligence sources were quoted as suggesting that Yuri Andropov, the Soviet Union's KGB chief, was Brezhnev's most likely successor. But the report quickly added that its estimate might well be wrong.

After months of debate and inaction, Haig's stated view that the succession offers a chance to reexamine in the broadest terms the relationship between Washington and Moscow appears to have won temporary ascendancy. The president's call for new arms limitation talks with Brezhnev or his successors suggests to many that the administration has decided to seize the initiative and treat the succession period as a time for friendly persuasion rather than the aggressive saber-rattling that critics say characterized earlier Reagan approaches to the Soviets.

But there are other competing schools of thought within the administration, and even the White House's most prominent hawks appear divided. Some hold that succession is an opportunity for the West to tighten the screws of foreign policy to intimidate and perhaps permanently cripple an implacable but weakened foe.

That particular line, identified publicly with hard-liners such as Defense Secretary Caspar W. Weinberger and Richard Perle, assistant secretary of defense for international security policy, would appear to have lost the battle with Haig except for one key fact--Reagan, for all his recent talk of arms control, is believed instinctively to share the hard-line view.

Even when he publicly calls for negotiations, the president can't resist making the point that he believes the Soviet Union is vulnerable and can be driven perhaps into collapse. "They're in a more desperate situation than . . . I had assumed they were economically," Reagan told a press conference March 31. "Their great military buildup has . . . left them on a very narrow edge." In last week's Eureka College speech, the closest to a conciliatory tone Reagan has ever taken with the Kremlin, he predicted that the Soviet buildup "in the end . . . will undermine the foundations of the Soviet system."

Perle, who sees Kremlin policy as a straight line moving relentlessly toward world domination, believes it matters little who sits at the top of the Soviet hierarchy. "Between contemporary Soviet history and Catherine the Great is a continuum, and I don't see any evidence that succession will mean an abrupt change," he said in a recent interview.

In Perle's view, the United States should apply the full weight of economic pressure on the Kremlin, denying it badly needed Western technology and trade credits, not to influence the outcome of succession but as realistic response to a foe. "It doesn't make any sense to devote our money to our enemy," he said.

Richard Pipes, chief Soviet expert on the staff of the National Security Council, shares Reagan's view that Moscow is weak, but draws a conclusion much different than Perle's. In recent published interviews, Pipes has suggested that Moscow's crippling economic problems may be the key to convincing the Kremlin's new leaders that the time has come for reforms and for a less adversary--and less expensive--relationship with the West. Unlike Perle, Pipes concludes that it makes a great deal of difference who runs the Soviet Union.

Critics say the indecision and confusion over succession reflects the administration's chronic inability to forge a firm, coherent policy toward the Soviet Union. The same policy-makers who strongly opposed an embargo on U.S. grain sales to the Soviets insist on sanctions on computers and trade credits--sending confusing signals to U.S. allies in Western Europe and to the Soviets themselves.

"Our policy has been a pendulum swinging from one extreme to another," said Walter Laqueur of Georgetown University, who notes that, by comparison, the Kremlin's policies have been consistent and predictable.

Jerry F. Hough of Duke University and the Brookings Institution believes that "there's a fundamental schizophrenia in this administration" between those who want to crush the Soviet Union and those who want to push it into reform. He describes the Perle side as "the-worse-the-better group, which holds that the more misery and the more workers who are killed in Poland, the sooner the whole thing will collapse."

Analysts suspect that the new initiatives ultimately will have little impact on who wins the succession contest. Nonetheless, most agree it is important for Washington to make gestures. "In a succession period you ought to be active, not just sit on your hands," said former deputy national security adviser William Hyland, who served under Henry Kissinger in the heady days of detente. "All kinds of factors come into play, and by staying involved you may at least slightly tilt things in the direction you want them to go."

Hyland believes the administration may already have squandered a rare opportunity to negotiate with the old Soviet leadership. "I think we've lost a year," he said. "We should have dealt with Brezhnev, and now it is probably too late. . . . "

Others scoff at the president's stated view that the Soviet Union can be pushed to collapse. One veteran State Department analyst said that despite Moscow's chronic economic problems, "it's still a nation rich in genius, science and culture, with a powerful economy--nobody's starving." His conclusion: "Basically our ability to influence them is far less than theirs to influence us, and in both cases it's on the margin. We can nudge them along with a carrot or a stick or a sheaf of grain, but I don't think we are in a position to force major change."