Demonstrators took to the streets of dozens of cities across the vast country on Saturday in largely peaceful rallies which called for an end to his rule and a rerun of a parliamentary election which they say was rigged to favor his ruling party.
From the Pacific port of Vladivostok in the east to Kaliningrad in the west, nearly 7,400 km (4,600 miles) away, they shouted with slogans such as "Putin must go!" and "Swindlers and thieves - give us our elections back!"
In a sign of recognition that the people's mood has changed, the security forces hardly intervened and city authorities allowed the protests to go ahead. State television broadcast footage of a huge protest in Moscow, breaking a policy of showing almost no negative coverage of the authorities.
But a statement from Putin's spokesman, Dmitry Peskov, gave no hint that the prime minister was about to shift direction to answer the protesters' demands or bow to their calls to annul the December 4 election and allow it to be rerun. It also made no reference to the protesters' calls for Putin to go.
"We respect the point of view of the protester, we are hearing what is being said, and we will continue to listen to them," Peskov said in a statement released late on Saturday.
That is unlikely to appease protesters who issued a list of demands at the Moscow rally, which police said was attended by 25,000 people and the organizers said attracted up to 150,000.
The demands included a rerun of the election, sacking the election commission chief and freeing people the protesters define as political prisoners, and the organizers called for a new day of protests on December 24. "I am happy. December 10, 2011 will go down in history as the day the country's civic virtue and civil society was revived. After 10 years of hibernation, Moscow and all Russia woke up," Boris Nemtsov, an opposition leader, wrote in his blog.
"The main reason why it was such a big success is that a feeling of self-esteem has awakened in us and we have all got so fed up with Putin's and Medvedev's lies, theft and cynicism that we cannot tolerate it any longer... Together we will win!"
It may not be that simple. The opposition has long been divided, most mainstream parties have little or no role in the rallies and keeping them up across the world's largest country is hard at the best times, especially in winter.
Most Russian political experts say the former KGB spy who has dominated the world's largest energy producer for 12 years is in little immediate danger of being toppled, despite anger over widespread corruption and the gap between rich and poor.
But they say the 59-year-old leader's authority has been damaged and may gradually wane after he returns as president in an election next March which he is still expected to win.
Although opinion polls show he is Russia's most popular politician, the protests indicate how deep feelings are over the December 4 election, in which Putin's United Russia won a slim majority and the opposition says it would have fared much worse if voting had not been slanted in the ruling party's favor.
"Putin has a formidable task. He has lost Moscow and St. Petersburg, crucial cities where everything usually starts," said political analyst and author Liliya Shevtsova. "He looks out of touch."
Putin, as president for eight years until 2008 and as prime minister since then, built up a strongman image by restoring order after the chaos in the decade after the Soviet Union's collapse in 1991. But he no longer seems invincible.
He could release the state's purse strings to satisfy the financial demands of some critics but many of the protesters in Moscow are middle-class people demanding more fundamental changes, including relaxing the political system he controls.
Answering calls to protests on social media sites, about 10,000 people protested on Saturday in St. Petersburg, Russia's second largest city, the biggest show of dissent outside Moscow.
People of all ages gathered in Moscow's Bolotnaya Square, many carrying white carnations as the symbol of their protest and some waving pictures of Putin and President Dmitry Medvedev declaring: "Guys, it's time to go."
Felix, 68, a retired military officer who declined to give his surname, said in Moscow he wanted Putin out, but had no hope this could be accomplished through elections.
"There is no way to change those in power within the electoral system they have set up, so we need to use other methods," he said.