Tens of thousands of demonstrators marched though Moscow under streaming banners, flags and balloons on Saturday to demand an end to President Vladimir Putin's long rule and to breathe life into their protest movement.
Protesters chanted "Russia without Putin!" as they marched through central Moscow in the first big rally since June.
Witnesses said opposition leaders appeared to have achieved their goal of attracting at least 50,000 people, enough to maintain the momentum of their movement but almost certainly too few to increase alarm in the Kremlin.
The protest underlined anger over what liberal Russians see as tough measures to smother the opposition since Mr. Putin began another six years in the Kremlin in May, but protests have not taken off outside big cities and the opposition is not united.
"Our main aim is to force the authorities to start a dialogue. The summer has gone, three months since our last march. Not a single demand has been met ... on the contrary, repressions have only gathered pace, more people have been arrested," far-left leader Sergei Udaltsov said.
Recalling a stunt in which Mr. Putin flew in a light aircraft alongside migrating cranes this month, Mr. Udaltsov said: "The president has detached himself from reality. He flies with cranes and just spits on the people from above."
Organizers released white balloons and doves into the cloudy sky before opposition leaders led the march down a leafy central Moscow boulevard behind a long banner declaring: "For early elections! Against repression!"
Protesters held big red, yellow and blue balloons decorated to look like ski masks worn by punk group Pussy Riot and with the words 'Free Pussy Riot' – a reference to three band members jailed after singing an anti-Putin protest in a church.
The protesters say Mr. Putin's return to the Kremlin after four years as premier is a setback for democracy because he could now be in a position to extend his rule of Russia to 24 years if he wins another term when his mandate expires in 2018.
That would keep him in power longer than Soviet leader Leonid Brezhnev, and opponents fear it would mean political and economic stagnation.
"People who lived in the Soviet Union are tired of absolute rulers. We're tired of a police state," said Alexander Kokhmansky, 79, as he marched.
Police were out in force across central Moscow, although the organizers received permission for the rally.
Sergei Yevseyev, 35, who works at a shipping firm, said he was protesting against Mr. Putin's tough leadership style and "the total lawlessness, total corruption, the lack of civil freedoms, the absence of independent courts and social injustice."
"When he first came to power we needed this toughness, but not any more. Society has stabilized," he said.
Others, some of them wearing T-shirts demanding the release of 17 protesters facing trial over a rally on May 6 that ended in clashes with police, said they were concerned that the steam had gone out of the nine-month-old protest movement.
"I really don't know how much we can change. I'm worried that the moment at which we could have really changed the atmosphere – that is when violence broke out in May – has been lost," said Ilya, a primary school teacher.
The demonstrations began last December over allegations of fraud in a parliamentary election won by Mr. Putin's party and turned into the biggest protests against him since he first became president in 2000, at times drawing up to 100,000 people.
Mr. Putin, who turns 60 next month, dismisses the protesters as a minority who do not have wide support across the country of more than 140 million, and his presidential election victory in March took the sting out of the demonstrations.
Apart from some minor electoral reforms carried out at the peak of the protests last winter, the Kremlin has resisted the protesters' calls for democratic and political change.
The opposition has struggled to unite its various groups including nationalists, leftists and middle-class liberals.
Even so, opinion polls show Mr. Putin's ratings, although still high by Western standards, are falling.
Speakers at a rally after the march criticized Mr. Putin over what they regard as his crackdown on dissent that includes new laws increasing protesters' fines, stiff punishment for defamation and new controls on foreign-funded campaign groups.
In another setback for the opposition, Gennady Gudkov, an outspoken Kremlin critic, was expelled from parliament on Friday on allegations of continuing business activities while holding a seat in the assembly. Alexei Navalny, another protest leader, has been accused of theft, and could face 10 years in jail.
"There is no more constitution in Russia. There are no more rights and there is no more parliament worthy of respect," Mr. Gudkov told the crowd to chants of "Shame!"
About 2,000 people protested in St. Petersburg, witnesses said, and Udaltsov said police detained some 15 protesters in the central city of Nizhny Novgorod.
A small protest took place in Yekaterinburg in the Ural Mountains, and witnesses said a rally in the Far East city of Vladivostok was much smaller than the opposition had hoped.