Women walk on March 3, 2012 past a door painted with a graffiti featuring Russia's Prime Minister and presidential candidate Vladimir Putin in Moscow. Russia on March 4 votes in presidential elections expected to send Vladimir Putin back to the Kremlin after his four year stint as prime minister. (JOHN MACDOUGALL/AFP/GETTY IMAGES)

The authoritarian system Vladimir Putin built is propelling him toward virtually assured victory in Sunday’s presidential election, but its increasingly visible weaknesses present grave challenges in the days ahead for him, Russia and the world.

Even independent pollsters predict a big first-round win for Putin, who was president from 2000 to 2008 and prime minister since. But his election to what is now a six-year presidential term only puts a veneer of invincibility on what many here see as the beginning of his decline, as unpredictable as it is inevitable.

“This term will be very hard for him,” said Olga Kryshtanovskaya, a sociologist and member of the dominant United Russia party. “I don’t think he’ll have a second term. I believe it will be a huge achievement if he stays in control until 2018 and gives power to a successor.”

By some measures Putin’s unwavering grasp of the past 12 years is as firm as ever: He has used his nearly limitless power to marginalize the opposition — serious contenders cannot emerge, and Putin decides who gets on the ballot, or even on state television.

The second-largest vote-getter Sunday is expected to be the Communist leader of two decades, Gennady Zyuganov, an unthreatening contestant who appeals mostly to those nostalgic for the sureties of the Soviet past. Voters are ambivalent about billionaire Mikhail Prokhorov, suspecting that the Kremlin planted him to divide the field. Though he has campaigned hard, that skepticism has undermined him. Attractive liberals have been prevented from running by compliant election officials.

That leaves the tens of thousands of disgruntled protesters, shaken out of their lethargy by accounts of widespread vote-rigging in the Dec. 4 parliamentary elections, with no one on the ballot who represents their interests.

The leaders of the street protests accept that this election is lost to them, but they say they have achieved an important first step by beginning to change the perception of Putin as invulnerable.

The image of Putin sternly instructing bureaucrats and accomplishing manly feats thoroughly dominates television screens, shaping public opinion among a wide swath of the population who spend more time there than on the Internet, where antagonism to Putin has flourished.

Despite the unprecedented public antipathy toward him that has arisen since Dec. 4, he is almost certain to be named the winner with more than 50 percent of Sunday’s votes, enabling him to avoid a second round of balloting later this month. The question is how much more.

The widespread belief that underlings will make sure Putin gets whatever number of votes he wants creates his greatest vulnerability: No one will really know how much support — or legitimacy — he has.

That perceived weakness could nurture a compensatory ferocity in foreign affairs — Putin has repeatedly blamed Americans in recent weeks for various problems at home, and Russia has blocked attempts by the United Nations to end the violence in Syria. For the United States, transportation routes through Russia to Afghanistan are at stake.

No alternative

Many Russians fear that once in office Putin will crack down on their burgeoning self-expression, though he denies any plans to do so.

“People are still telling us we’ll see the reformed Putin,” said Harley Balzer, a Russia expert at Georgetown University, “but I have my doubts — although I would like to be wrong.”

A recent pattern of government appointments, especially at the mid-level, raises concern. “It makes a pretty convincing picture that Putin is putting into place people who could carry out a fair degree of repression,” Balzer said in a telephone interview from Washington.

A week ago, news media published reports that Putin would get 66 percent of the vote. The figure came from the independent Levada Center, which said it represented only those who had already decided on their candidate and did not include the one-third undecided.

Still, Lev Gudkov, the director of the center, estimated in an interview that Putin was likely to get about 63 percent. The high percentage reflected both control of television and his ability to cast himself as a candidate without alternatives. Gudkov predicts Putin will take less than 20 percent of the vote in Moscow, where citizens have greater access to the Internet and there is a larger, informed middle class. “It’s very different in poor regions and small towns,” Gudkov said. “The only source of information is state television.

People tend toward conformity, and demonstrating their loyalty to those in power.

“We do not live in a free country,” he said. “It’s an authoritarian regime with manageable and manipulated public opinion. In no way is the election fair.”

‘On the edge of a cliff’

Grigory Golosov, a St. Petersburg political scientist, said the electoral fraud in December was mild — although the ruling United Russia party remained dominant, it lost its usual huge margins.

“The normal routine for Russian authorities has been to publish the poll results and then tell local authorities to produce those results,” he said. “In December it didn’t work, but that doesn’t mean it won’t work now. They will do everything to make sure Putin wins in the first round.”

Putin’s allies often contemptuously describe those who oppose him as a coddled middle class. But he may need them as he confronts steep challenges in the years ahead.

“Putin has lost the part of society that defines how society will develop,” said Alexei Mazur, a political scientist in Novosibirsk.

Russia’s spending exceeds its income, which is dangerously dependent on oil and gas revenue. It loses too much money to corruption, has no manufacturing sector to speak of, and is losing billions of dollars of capital every month. Its reliance on energy extraction — intricately tied up with the level of corruption — will inevitably reduce it to the level of a Persian Gulf monarchy, said Antoine Heuty, deputy director of Revenue Watch, a nonprofit group based in New York.

“Russia is standing on the edge of a cliff,” Heuty said. “It just doesn’t see the precipice.”