MOSCOW - In an outcome long predicted, Russian voters overwhelmingly granted Vladimir V. Putin a six-year term as president on Sunday, setting the stage for a far more suspenseful postelection confrontation between Putin and opposition groups.
“We have won,’’ Putin declared to a huge throng of supporters outside the Kremlin walls, a tear running down his cheek. “We have gained a clean victory!’’ He added, “We won! Glory to Russia.’’
Putin has been Russia’s preeminent leader for 12 years, serving two terms as president from 2000 to 2008 before his current term as prime minister. But the prospect of more protests, starting with a rally on Monday night in Pushkin Square in central Moscow, threatened to undercut his promise of stability.
Independent election observers and opposition leaders said there were widespread complaints of vote-rigging, and reports of Putin supporters being bused to multiple polling places to cast votes.
Some opposition leaders called for protests beyond those allowed by government permits, raising the prospect of a sharp response from the authorities.
Anticorruption blogger Aleksei Navalny said he would lead an unsanctioned march to the Kremlin after a rally scheduled for Monday. He has called for a permanent encampment of demonstrators like those created by the Occupy movements in the West. “People need to go out on the streets and not leave until their demands are met,’’ he said in a television interview.
With 77 percent of ballots counted, Putin had won 64.9 percent, the Central Election Commission said, comfortably above the 50 percent needed to avoid a runoff. Not long after the polls closed in Moscow, tens of thousands of Kremlin supporters met in Manexhnaya Square for a victory celebration and concert.
The voting took place under heightened vigilance, after a disputed parliamentary election in December that helped set off the huge opposition protests. On Sunday, thousands of election observers took up posts across the country, most of them - in accordance with Russian election law - aligned with a candidate.
By some tallies, there were more than 3,000 complaints of violations, including “carousel voting,’’ in which the same people cast ballots at multiple locations, and “centralized voting’’ in which managers of factories, schools, hospitals, and other large organizations pressure employees to vote for a specific candidate. In some cases, ballots were collected at the workplace.
And again there were statistically improbable results from the North Caucuses, which is home to 6 percent of the Russian electorate and where Putin and his party have previously won close to 100 percent of the vote with abnormally high turnout.
There was no expectation that the complaints or improbable tallies would alter the results.
Even with opinion surveys showing Putin well-positioned to win the presidency, the political playing field has been Russia’s most unstable since 1996, when President Boris N. Yeltsin was forced into a second-round runoff by the Communist leader, Gennady A. Zyuganov.
Zyuganov, who was a candidate again this year, declared the results illegitimate even before all the votes were counted. “It was illegitimate, unfair, and not transparent,’’ he said. “I will not congratulate anyone.’’
Many voters said they were ambivalent, indicating a general sense that there was no viable alternative to Putin. “I will not say who I am voting for,’’ Anastasia Ryabukhina, 20, a student at the Academy of Labor and Social Relations, said at a polling station in Moscow. “But think about it yourself: Of all of them, Putin is the most realistic candidate.’’
Putin, who did little traditional campaigning and refused to debate his opponents, nonetheless engaged in some of the most aggressive election-year politicking of his career. He postponed for six months the annual increase in household utility charges, the largest expense for most Russian families; increased pensions and military salaries; and promised an avalanche of new government spending.
He employed anti-American rhetoric, accusing Washington of trying to stoke revolution in Russia as well as in the Middle East. He appealed to nationalist pride.
“We still have much to do for our Russia and for our people,’’ he thundered at a rally. “And we will do it based on the talent of our people, on our great history, which is written with the blood and sweat of our forefathers.’’
Still, Putin’s victory never seemed in doubt. He faced three well-worn opponents he had defeated in the past - including Zyuganov - and one newcomer, Mikhail D. Prokhorov, a billionaire industrialist and owner of the New Jersey Nets basketball team, who mustered the 2 million signatures to get on the ballot but had no party to support him and no political experience.