The opposition RPR-Parnas party looks set to win seats in the Yaroslavl regional legislature, taking almost 6 percent of the vote at Sunday's elections, with 95.5 percent of ballots already counted.
RPR-Parnas, with a ticket headed by prominent Kremlin critic Boris Nemtsov and whose members have organized nationwide street protests against President Vladimir Putin, was only allowed to register as a party last year after the European Court of Human Rights ruled that the Russian government had unfairly denied it registration numerous times.
Success in Yaroslavl, a region close to Moscow, would be welcome for a party that previously has only won seats in the Barnaul city legislature in Siberia.
According to the preliminary count, 39.8 percent of the Yaroslavl region electorate voted for United Russia, 11.65 percent for the Communist Party, 10.23 percent for A Just Russia, and 5 percent for the Liberal Democratic Party, Vedomosti reported.
A party needs at least 5 percent of the vote to claim seats in the 50-member legislature. Half of the seats are elected on party tickets and the other half as single-member constituencies.
United Russia, the Liberal Democratic Party, the Communist Party and Patriots of Russia were all represented in the previous legislature. Patriots of Russia's results fell in this election, with the party expected to draw only 4 percent of the vote.
The Yaroslavl race drew national attention in August when elections officials denied the registration of billionaire Mikhail Prokhorov's increasingly popular Civil Platform party, saying the party had failed to open an elections bank account on time.
The party, however, said that its representatives were prevented from opening the account by local police, who it said detained them until the deadline had passed. Local authorities denied the allegation.
The Civil Platform ticket had listed about 50 candidates headed by Yevgeny Urlashov, a former United Russia member who turned against the ruling party in 2012 and won the post of Yaroslavl mayor as an independent candidate.
Urlashov was fired from the post in July and arrested on suspicion of corruption and extortion, allegations that Urlashov has said were fabricated to discredit his party prior to the elections.