MOSCOW -- About a dozen protesters were arrested by the police on March 10 as several thousand pro-democracy demonstrators attended a rally to denounce the March 4 presidential election that was won by Prime Minister Vladimir Putin.
Sergei Udaltsov, leader of the Left Front movement, was among those arrested while trying to conduct an unsanctioned march on the margins of the main, officially sanctioned demonstration.
Udaltsov has been charged with failure to obey a police officer and could face up to 15 days' administrative detention. He had called on supporters to leave the sanctioned rally and march to Pushkin Square to "discuss" the latest protest.
Earlier, Moscow police detained about 25 ultranationalists who tried to hold an unsanctioned march in a nearby part of the city.
At the main, sanctioned protest on Moscow's Novy Arbat Street, demonstrators carried white balloons and banners and wore white ribbons to highlight alleged falsification of the presidential election and the December 2011 legislative elections.
There was a heavy police presence surrounding the demonstration, as the Interior Ministry reported some 2,500 troops would be on duty.
"I counted about 19 buses and trucks with police in them on the main Novy Arbat track. There's a police helicopter -- actually, there's a helicopter in the sky that presumably is police because you can't fly in Moscow skies," RFE/RL correspondent Tom Balmforth reported.
Vladimir Putin officially received 63 percent of the vote in his election to a third term as president.
Demonstrators repeated calls for new elections and for Putin to stand aside. Udaltsov told Reuters that the current Russian authorities were "illegitimate."
"We don't recognize the current authorities, the elected Duma, the elected president as legitimate. So we should act according to that position," Udaltsov said.
"The quicker we liberate the country with peaceful, but decisive methods, from the illegitimate, unlawful authorities, the better for all of us."
Putin was awarded about 63 percent of the vote in the election, which international election monitors have said was clearly skewed to Putin's advantage.
Opposition leader Vladimir Ryzhkov also told the crowd that the legislative and presidential elections were illegitimate and said the movement would continue to press its demands.
"So far the authorities have no intention of moving toward serious, complex reforms. And they do not intend to hold new snap parliamentary and presidential elections," he said. "We will continue to demand from them systemic political reforms and new elections. We will continue to demand the release of all political prisoners."
WATCH: Police detained dozens of protesters trying to conduct an unauthorized march after an early, officially sanctioned opposition rally in Moscow.
'What Are We Here For?'
Police estimated the crowd in Moscow to be about 10,000 people, while demonstration organizers put the figure at 25,000-30,000, significantly lower than was seen at demonstrations in December and January that brought up to 100,000 people into the streets.
There were smaller demonstrations in other cities around Russia on March 10. In Nizhny Novgorod, about 100 people gathered in an unsanctioned demonstration and as many as 60 were detained by the police.
In St. Petersburg, about 40 people were detained trying to hold an unsanctioned demonstration. In Yekaterinburg, at least 2,500 people demonstrated, and no arrests were reported.
Speaking to Reuters in Moscow, one demonstrator explained his reasons for protesting:
"Putin destroyed the constitution, and went for a third term. And in our country, not the higher court, nor the constitutional court can say to him that he has no right to go for a third term," he said. "And that's why we have this disarray in society."
In comments to RFE/RL, another demonstrator who identified himself as Sergei, a 49-year-old businessman, said he was demonstrating for free elections. "I want Russia to be a free country. I don't want them to deceive me during the elections," he said. "I want it to be so that when I vote for something, my vote isn't stolen. I want it to remain where I put it. That's all."
A woman holds a sign featuring Adolf Hitler, Josef Stalin, Muammar Qaddafi, and Vladimir Putin, and below it says "Kaput!"
The opposition movement is struggling to maintain its momentum in postelection Russia. Speakers on March 10 had difficulty rallying the crowd.
High-profile socialite Ksenia Sobchak told the crowd that it was time for the opposition in Russia to stop protesting against the authorities and to lay out its own positive program.
"We all know what we are against," she said. "Now we must very quickly formulate what we are for. We are for judicial reform, for a free press, for broad political reforms."
In comments to Interfax, opposition leader Boris Nemtsov -- who did not attend the rally because of a cold -- said it was now necessary for the opposition to prepare for upcoming elections at all levels -- local, mayoral, and gubernatorial.
He supported a call made at the demonstration by Udaltsov to hold a million-person rally in Moscow on May 1.
"Definitely, it is not a bad idea," Nemtsov said. "Of course, it is hard to say if a demonstration with 1 million people could be pulled off, but making a clear, unified demonstration right on the eve of the presidential inauguration would be very good."
Putin is expected to be sworn in as president in the Kremlin on May 4.
Many of the demonstrators were supporters of oligarch Mikhail Prokhorov, who came in third in the presidential race. Sergei, 49, is a Moscow businessman who said he was not worried that the crowd at the demonstration seemed noticeably smaller than the one that gathered the day after the election.
Protesters rally on Novy Arbat Street in central Moscow.
"It is completely to be expected that the level of activity on the street inevitably has to fall. The people who come here have a lot of things to do, as a rule," he said.
"I have my own business, for example; other people have a lot of work. We can't come out into the streets every week, can we?"
Nonetheless, the crowd in Moscow represented a broad spectrum of the country's political opposition united under the For Free Elections slogan.
""All the various parties are represented here. There's loads of nationalist flags, Solidarity flags, Yavlinsky flags. There's even a Facebook flag -- I don't know what the message is there," RFE/RL's Balmforth noted.
"There isn't really much of a festival atmosphere or jovial atmosphere as there was the other day," at the rally on March 5.
It was estimated that some 20,000 people participated in the March 5 Moscow rally and some 200 people were detained by police. There were smaller protests in other cities, and police arrested about 300 demonstrators in St. Petersburg.
Another participant in the demonstration, who identified herself as Yektarina and said she was an architectural historian, expressed hope that Russia is moving into a period of greater democratic development.
" I know the history of Moscow well -- particularly, the Soviet period and the history of architecture -- and I know that after difficult periods of suffering there come periods of liberation and I hope that now we are emerging onto the general path of world development," she said.
"At least, I hope so."
With RFE/RL's Russian Service and AP, Reuters, ITAR-TASS, and AFP reporting