Moscow is not a city of ghosts, but on Saturday, tens of thousands of figures were seen marching in the Russian capital chanting, "We exist! We exist!" That might seem like an exercise in the obvious. But the crowd thought a reminder was in order for Prime Minister Vladimir Putin, who has generally regarded his critics as though they were invisible.

He can see them now. In last week's parliamentary election, his United Russia Party suffered a humiliation, losing 77 of its 315 seats and getting less than a majority of all votes -- down from 64 percent four years ago.

It's embarrassing enough to do poorly in an honest election. Putin's party managed to crater despite vigorous measures to rig the vote. In the province of Chechnya, United Russia somehow garnered 99 percent at the polls.

In the city of Rostov-on-Don, state TV reported its share of the vote at 146 percent.

Putin and his sidekick, President Dmitry Medvedev, defended the integrity of the election, but they were a tiny chorus. Opposition groups posted video of ballot-stuffing and other tactics that would make a Chicago precinct captain smile. One man said he was paid to cast 45 ballots for United Russia.

A Russian election watchdog group, Golos, said United Russia "achieved the majority mandate by falsification." International observers from the Organization for Security and Cooperation in Europe found "frequent procedural violations and instances of apparent manipulation."

They reported, "The contest was also slanted in favor of the ruling party, the election administration lacked independence, most media were partial and state authorities interfered unduly at different levels." Oh, in case Putin is reading: They didn't mean that as praise.

When protesters took to the streets, he was reduced to claiming the demonstrations occurred at the behest of Secretary of State Hillary Clinton. She had pronounced the balloting "neither free nor fair" but had never before been known for her ability to incite Russians (or Americans) to rise up against their leaders.

Putin served two four-year terms as president, but the Constitution barred him from a third consecutive term. So in 2008, he traded jobs with Medvedev, whose assignment, ably performed, was to let his patron remain in control. In September, Putin announced he would run for president in March for a six-year term, as the constitution now stipulates.

If things go his way, Putin could stay in power until 2024. By then -- you never know -- he might somehow contrive to stay longer.

But for the first time, things are not going his way. United Russia is now popularly known as "the party of swindlers and thieves." A few weeks ago, appearing at a martial arts match, he was booed on national TV.

The protests in Moscow following the parliamentary election were the biggest of the post-Soviet era -- so big that the police had to refrain from arresting people, and "too large to be edited out of the evening news, which does not normally report on criticism of Putin," said The New York Times.

The outpouring was accompanied by similar rallies in cities across Russia. Putin has managed to prod the various small, diverse opposition factions, from liberals to Communists to right-wing nationalists, into uniting against him.

In the aftermath, billionaire businessman Mikhail Prokhorov announced he would run for president. Such is the strange nature of Russian politics that some experts regard him as a fake opponent inserted to help Putin by siphoning support from real ones.

But the coming election could nonetheless serve to mobilize the opposition. Stephen Sestanovich, the U.S. ambassador-at-large to the former Soviet states in the 1990s, said on the Council on Foreign Relations website that the critics' anger is unlikely to subside because "they have something new to focus on. They are mad and they have a way to express it, which is to get involved and deny Putin a first-ballot victory."

If he were held to less than a majority of the votes, he would have to face a single opponent in a runoff -- in which case things might veer out of his control. Putin enjoyed considerable popularity before the parliamentary elections, but his coarse tactics have doubtless eroded it.

Russians have endured many trials over the past century, including the persistent denial of the right to govern themselves. It will come as news to the prime minister that they may not endure it forever.