Opponents have accused Russian authorities of mass fraud today after the ruling United Russia party, which supports President Vladimir Putin, won a bigger than expected parliamentary majority despite unease over living standards.
With over 99% of ballots counted, the Central Election Commission said United Russia had won nearly 50% of the vote, with its nearest rival, the Communist Party, taking just under 19%.
The scale of the victory means United Russia will have more than two-thirds of deputies in the 450-seat State Duma lower house of parliament. This will enable it to continue to push through laws without having to rely on other parties.
United Russia, a party that Mr Putin helped found, had always been expected to win. Its most vociferous critics, allies of jailed Kremlin critic Alexei Navalny, were prevented from taking part after a court branded them extremists in June.
Pre-vote surveys had suggested that discontent over years of faltering living standards and corruption allegations would dent United Russia's support. In the event, near final official results showed it securing around only 4% less than the last time a similar election was held in 2016.
Some Moscow-based Communists who felt cheated called for a protest in the Russian capital this evening. The central square they named as the venue was sealed off by police beforehand.
One of the disappointed Communists, Mikhail Lobanov, had been far ahead, based on a regular voting tally, but suddenly learned he had lost out to a United Russia candidate once electronic votes were added in after a long delay.
"I know that such a result is simply not possible," Mr Lobanov wrote on Twitter, calling for people to gather to discuss "next steps".
Candidates opposed to United Russia in Moscow had been ahead in more than half of 15 electoral districts, but all lost after electronic voters were added in.
"With such a colossal number of violations, the results of the State Duma elections cannot be recognised as clean, honest or legitimate," said Lyubov Sobol, a Navalny ally.
Ms Sobol had hoped to run for parliament herself but Mr Navalny's allies were barred from taking part after the extremism designation. Critical media and non-governmental organisations were also targeted by the authorities in the election run-up.
Mr Navalny's allies had tried to drain support from United Russia with an online tactical voting campaign which the authorities had tried to block.
Electoral authorities said they had voided any results at voting stations where there had been obvious irregularities and that the overall contest had been fair.
According to Ella Pamfilova, the head of the election commission, the vote was exceptionally clean and transparent. She told Mr Putin she would look into any complaints before declaring final results on Friday.
Mr Putin gave a short statement, thanking voters after the Kremlin had hailed the result, saying United Russia had confirmed its role as the leading party. The Kremlin said the election had been competitive, open and honest.
The outcome is unlikely to change the political landscape, with Mr Putin, who has been in power as president or prime minister since 1999, still dominating before the next presidential election in 2024.
Mr Putin has yet to say whether he will run.
The 68-year-old leader remains a popular figure with many Russians crediting him with standing up to the West and restoring national pride.