(CBS/AP) MOSCOW - Vladimir Putin has claimed victory in Russia's presidential election, which the opposition and independent observers say has been marred by widespread violations.
Putin made the claim at a rally of tens of thousands of his supporters just outside the Kremlin, thanking his supporters for helping foil foreign plots aimed to weaken the country.
Putin tallied 58-59 percent of Sunday's vote, according to exit polls cited by state television.
Communist Party candidate Gennady Zyuganov received about 18 percent, according to the survey, and the others nationalist Vladimir Zhirinovsky, socialist Sergei Mironov and billionaire Mikhail Prokhorov were in single digits.
With just over 20 percent of all precincts counted, Putin was leading the field with 63 percent of the vote, the Central Election Commission said.
Putin, president from 2000 to 2008, was expected to easily win the Sunday election against four challengers. But if credible evidence of vote manipulation emerges, it would bolster the determination of opposition forces to continue the unprecedented wave of protests that arose in December.
The independent elections watchdog agency Golos said it was receiving reports of so-called "carousel voting," in which busloads of voters are driven around to cast ballots multiple times.
"There have been many people voting more than once, driven around in buses in large numbers" in Moscow, said Golos head Lilia Shibanova, who said similar reports had been received from Novosibirsk, Russia's third-largest city, and the city of Barnaul in southern Siberia.
"We, of course, expected carousels, but not on this scale," Alexei Navalny, one of the opposition's most charismatic leaders, said on Twitter.
Allegations of widespread vote fraud in parliamentary elections set off the massive protests against Putin, who has remained Russia's paramount leader despite stepping down from president to prime minister four years ago due to term limits. They were the largest public show of anger in post-Soviet Russia and demonstrated growing frustration with corruption and political ossification under Putin, who as prime minister has remained Russia's dominant politician.
Golos' website recorded well more than 1,000 complaints of irregularities, including voter lists of questionable validity and nonfunctioning cameras in voting stations.
Web cameras were installed in Russia's more than 90,000 polling stations after the December election, a move initiated by Putin in response to complaints of ballot stuffing and fraudulent counts. Those elections saw his United Russia party retain its majority in parliament, though substantially reduced from its previous overwhelming control.
It was unclear Sunday to what extent the cameras would be effective in recording voting irregularities or questionable counts. The election observation mission of the Organization for Security and Cooperation in Europe noted skepticism in a report on election preparations.
"This is not an election ... it is an imitation," said Boris Nemtsov, another prominent opposition leader.
But despite the increased dismay, opinions polls have shown Putin positioned to easily defeat four other candidates and return to the presidency. Putin presided over a significant growth in Russia's prosperity and growing stability that contrasted with the disorder and anxiety of the 1990s, when Boris Yeltsin led Russia's emergence from the wreckage of the Soviet Union.
"Under Boris Nikolayevich, life was simply a nightmare, but, you know, now it's OK. Now it's good, I'm happy with the current situation," said 51-year-old Alexander Pshennikov, who cast his ballot for Putin at a Moscow polling station.
But other voters were tired of the heavy-handed ways of the one-time KGB spy. Natalya Yulskaya, 73, said she voted for billionaire Mikhail Prokhorov as a protest gesture against Putin.
"I know the KGB will be in power ... but I gave it a try," she said.
Putin has dismissed the protesters' complaints, portraying them as a coddled minority of urban elitists and as dupes of Western countries that he claims want to undermine Russia.
Putin's disdain for the protesters became more marked in the last week of campaigning, as he publicly suggested the opposition was willing to kill one of its own figures in order to stoke outrage against him. That claim came on the heels of state television reports that a plot by Chechen rebels to kill Putin right after the election had been foiled. Some of Putin's election rivals dismissed the report as a campaign trick to boost support for him.
Protests after the election appear certain.
"These elections are not free ... that's why we'll have protests tomorrow. We will not recognize the president as legitimate," said Mikhail Kasyanov, who was Putin's first prime minister before going into opposition.
The Interior Ministry called in 6,000 police reinforcements to the capital from other regions, the state news agency ITAR-Tass reported Friday. There were no immediate reports of trouble on Sunday, although police arrested three young women who stripped to the waist at the polling station where Putin cast his ballot; one of them had the word "thief" written on her bare back.