MOSCOW - Tens of thousands of people fed up with Vladimir V. Putin's domination of Russian politics and his perceived arrogance toward them jammed one of Moscow's broadest avenues Saturday for a giant protest, vowing to keep building the pressure until the longtime leader is driven from power.

"Russia without Putin!" the crowd chanted as it protested alleged fraud during Dec. 4 parliamentary elections that saw Prime Minister Putin's United Russia party garner nearly 50 percent of the vote.

The demonstration, the largest in Russia's capital since the breakup of the Soviet Union in the early 1990s, was a direct rebuff of Putin and President Dmitry Medvedev, both of whom in recent days had sought to mollify critics by promising political changes.

Many in the Moscow crowd said they were simply tired of the autocratic attitude of Putin, who was president for eight years beginning in 2000 and is seeking a return to the presidency in an election scheduled for March.

Speakers at a central platform, their remarks booming out from huge screens placed along the protest route, ratcheted up their rhetoric and declared their intent to build on their momentum in coming months.

"In 2012, we will clear the Kremlin of swindlers and thieves," vowed opposition leader Garry Kasparov, the former world chess champion.

The rally was held along Sakharov Avenue, named for dissident nuclear scientist Andrei Sakharov. Thousands of people also protested in cities and towns across Russia.

"This movement shows us that the country has changed," said Vladimir Lukin, a presidential envoy on human rights, who came to the Moscow rally as an observer. "The authorities at last realized how many people want changes."

Young and old attended, sacrificing Christmas shopping, family brunches, skating and skiing excursions to join the latest vote-fraud protest in what some have begun calling the Russian Winter, an allusion to the Arab Spring in the Middle East.

Winds of change have been blowing through Russia since the Dec. 4 polling, which was marred by allegations of foul play. Wide-scale protests began a day later and were at first brutally dispersed by police, who arrested several hundred activists.

On Dec. 10, a peaceful protest in Moscow drew a then-unprecedented 60,000 people, most of them young adults and middle-class citizens who had previously shunned politics.

Since then, the results of the parliamentary vote have been annulled at 21 polling stations, and investigations continue. The Presidential Council on Human Rights demanded Friday that the chairman of the central election commission, a staunch Putin ally, resign.

Riot police stayed on side streets Saturday and did not display weapons or shields.

As the crowd formed along the mile-long protest route, one police officer said to a colleague, "If they decide to march on, can we contain them, do you think?" The other shook his head in disbelief and replied: "We won't last a quarter of an hour with this crowd. We will need an army to hold them."

Activists appeared especially disturbed by recent remarks from Putin in which he compared the white ribbons worn by street protesters to condoms, and a literary allusion in which he portrayed himself as a wise and powerful python from Rudyard Kipling's The Jungle Book and protesters as disorganized and cowardly monkeys.

Deputy Kremlin staff chief Vladislav Surkov has since sought to repair the damage by saying that protest participants represent "the better part of our society."

"They can't be condescendingly brushed away," he said in an interview with the pro-Kremlin daily Izvestiya on Thursday, acknowledging that "the tectonic structures of the society have started to move."

Nonetheless, the Saturday protest took on a new level of vitriol, with protesters wearing white ribbons, badges, balloons - and more. One man carried a poster of Putin with a huge condom wrapped around his neck. Others carried posters of Putin next to such late dictators as Moammar Gadhafi and Kim Jong Il.

Several speakers, appearing emboldened by the sheer crowd size threatened to grab power if their demands are not met. Protest leaders estimated the crowd size at 120,000; the Moscow Police said it was 29,000.

"We have enough people here to take the Kremlin . . . right away!" shouted blogger Alexei Navalny, who was released from jail last Tuesday after a 15-day stay for his actions at previous protests.

"If the swindlers and thieves continue robbing us and lying to us, we will ourselves get back what belongs to us," said Navalny, who has become well-known for taking on state-owned business giants Gazprom and Rosneft for alleged corruption.

"We don't want to scare anyone, but we believe that next year there will be a peaceful change of power, and power will belong to . . . the people," he said, to the loudest applause of the day.

Navalny promised one million protesters at future rallies, which he said would continue until the Kremlin gives in to the movement's demands, including the immediate release of all political prisoners and the voiding of the tainted election results.

Opposition leaders also called for new elections and said Putin should not receive a single vote in March.

Participant Vladimir Mikhailov, 47, a medical-equipment company director, said he was overwhelmed by the size of the rally in Moscow.

"I am so happy to see so many people here who are not afraid to come and protest against lawlessness and corruption," said Mikhailov, who dropped his United Russia membership just before the parliament vote.

Russian democratic movement veteran Viktor Sheinis said it would be "a huge loss for the country if this movement doesn't achieve anything soon and its tremendous drive and enthusiasm is eventually wasted."

"That," added Sheinis, a coauthor of the 1993 Russian Constitution, "is what the authorities are counting on."