It's a tough race in District 50 between Oleg Sergeyev, Oleg Sergeyev and Oleg Sergeyev.

Sergeyev the incumbent is running for his seat in St. Petersburg's city assembly in today's first round of municipal elections. He faces two candidates of the same name who represent no parties, made no public appearances and did not use their allotment of free television time.

The confusion created by their candidacy is only one of a cavalcade of dirty tricks in a campaign marked by vote buying, absentee ballot-box stuffing and intimidation. The election is also being held under the shadow of a headline-making assassination. The polls opened today under snow and heavy police guard.

Many Russians regard today's vote as the opening battle in a long and tense political season. The sinister atmosphere of the election has taken on significance far from the winding canals of this stately city. National parliamentary elections are scheduled next year, and the presidential vote for 2000, assuming ailing president Boris Yeltsin serves out his four-year term. If dirt buries sophisticated St. Petersburg, once the vanguard of Russia's young democracy, it can easily overwhelm future votes elsewhere, observers reason.

The drama heightened dramatically on Nov. 20 when gunmen ambushed and killed Galina Starovoitova, a leading democracy activist who represented the city in the Duma, the lower house of Russia's parliament. The shocking assassination underlined the spiraling violence in Russia's second-biggest city. More broadly, it raised the question of whether orderly democracy can survive the nationwide plague of economic depression, crime, corruption, resurgent antisemitism and political decay.

"In some sense, the hopes for democracy rest in St. Petersburg today," said Leonid Kesselman, a sociologist and political columnist. "The Russian ship is turning away from the democratic course, and this city can help right it."

All 50 seats in the municipal assembly were up for grabs in today's first-round vote. About 600 candidates were running. Results are not expected until Monday, and many races are expected to go to runoff elections to be held Dec. 20.

The assembly is unusual because, under a new city charter, it can hold the city's executive branch accountable for its actions. Such balance-of-power politics are rare in Russia. Authoritarian mayors, governors and the president all exercise vast powers of rule-by-decree, while legislatures are limited largely to budget oversight, if that.

The three-Sergeyev race illustrates the street-level stakes. The incumbent, a physician, fought to reform the city's procurement of prescription drugs for the needy. He charged that purchases were made from a cabal of companies that charged high prices and delivered substandard goods.

In April, unknown assailants beat him up outside his apartment and fractured his ribs and skull with a truncheon. He was hospitalized for two months. Sergeyev declared his candidacy anyway, but his campaign was quickly mired in a muck of brazen dirty tricks: false invitations put out under his name enticing voters to free food handouts, the appearance of the two mystery Sergeyevs, their offers of money to voters in advance of the balloting -- and a bonus if they won.

"This is a clear attempt by criminals to steal this election," said Sergeyev, a two-time assembly member. "It is not enough anymore for gangsters to influence politics. They want to take direct charge."

Sergeyev's phantom rivals supposedly exist. One is a retiree, the other an unemployed laborer, according to registration records.

And he is not alone in his campaign against such false doubles -- called dvoiniki in Russian. They appeared in several other districts. An incumbent in favor of housing reform, Sergei Andreyev, is facing three mystery candidates with the same name. Former assembly speaker Yuri Kravstov is running against a student named Yuri Kravstov. Reformist candidate Alexander Belyaev was opposed at one point by an identically named sea captain who withdrew and announced he had been given $900 to declare his candidacy. He declined to say who paid.

Candidates for the centrist Yabloko bloc find themselves on the ballot next to challengers from a new group called Yabloko St. Petersburg that listed headquarters addresses in a residential area and an industrial district. Both turned out to be false.

At a polling station near the Mariinsky Theater, a woman scanned a candidate roster and noted there were two Albert Baranovs listed. "Can someone help me?" she asked plaintively.

"This is clearly being done to reduce the chances of respectable candidates," said Yelena Tsembalistova, a medical researcher. "I don't know who is doing it, but they are hungry and powerful."

In St. Petersburg, the growing blight on democracy stems from two struggles, observers say. First, Vladimir Yakovlev, the mayor -- or governor, as the post is known here -- has resisted the city legislature's drive to hold him accountable for city business.

Aides say Yakovlev is taking a neutral stand in the election, but the hands-off approach means nothing is being done to curb fraud. The city prosecutor's office has taken no steps to punish either false candidacies or vote-buying schemes. "The governor would have been criticized if he intervened, and he's being criticized for not intervening," said Vice Governor Alexander Potekhin.

In addition, gangsters are battling to control municipal resources -- everything from real estate to the port to cemeteries to the supply of fuel for public transportation. New groups are making war on established organized criminals. Assassination is a frightening tool of choice.

Last year, a sniper killed the city's privatization chief, Mikhail Manevich, on Nevsky Prospect, St. Petersburg's main commercial street. This year, an official in charge of cemeteries was blown up by a remote control bomb. So was an oil middleman with city hall connections. Then came the assassination of Starovoitova, who had been campaigning against Yakovlev and whose newspaper, Sebernaya Stalitsa, had published exposes of city hall wrongdoing.

None of the killers has been apprehended.

Anti-Yakovlev forces and anti-crime campaigners may benefit from the outcry over Starovoitova's death. Before the assassination, 20 percent of the city's 3.5 million voters had been expected to go to the polls; figures released tonight put turnout at 38 percent.

But the forces of reform are divided. At least one anti-crime front was formed, but it is difficult to know who among the dozens of candidates represents what.

"One problem is that while there are anti-crime groups, there is no way of knowing what is the pro-crime list. No one knows who is paying for what. We are operating in the dark," said Kesselman. CAPTION: Despite two pairs of glasses, Mikhail Borodinsky, 75, has a hard time finding his candidate in the voting list in St. Petersburg's municipal election. Nearly 600 candidates were on the ballot, including many with identical names. ec