MOSCOW - Vladimir Putin's party won a crushing victory in parliamentary elections yesterday, paving the way for the authoritarian leader to remain in control even after he steps down as president.

The vote followed a tense Kremlin campaign that relied on a combination of persuasion and intimidation to ensure victory for the United Russia party and for Putin, who has used a flood of oil revenues to move his country onto a more assertive position on the global stage.

"The vote affirmed the main idea: that Vladimir Putin is the national leader, that the people support his course, and this course will continue," party leader and parliament speaker Boris Gryzlov said after exit polls were announced.

Several opposition leaders accused the Kremlin of rigging the vote, and the Bush administration called for a probe into voting irregularities.

Communist Party leader Gennady Zyuganov called the election "the most irresponsible and dirty" in the post-Soviet era, and party officials vowed to challenge the results.

With ballots from 72.5 percent of precincts counted, United Russia was leading with 63.1 percent, while the Communists trailed with 11.7 percent, the Central Election Commission said. Exit polls seemed to corroborate the partial results.

The Kremlin portrayed the election as a plebiscite on Putin's nearly eight years as president - with the promise that a major victory would allow him somehow to remain leader after his second term ends next year.

Putin is constitutionally prohibited from running for a third consecutive term, but he clearly wants to stay in power. A movement has sprung up in recent weeks to urge him to become a "national leader," though what that would entail is unclear.

Pollsters said United Russia's performance would give it a majority of 306 seats in the 450-seat State Duma, or lower house. The Communists would have 57 seats.

Two other pro-Kremlin parties - the nationalist Liberal Democratic Party and populist Just Russia - also appeared to have made it into parliament.

One Liberal Democratic Party deputy will be Andrei Lugovoi, an ex-KGB officer and chief suspect in the poisoning death of Kremlin critic Alexander Litvinenko in London last year. Russia has refused to hand Lugovoi over to Britain.

The Duma seat gives him immunity from prosecution. *