Hundreds of supporters of Russian opposition leader Alexei Navalny have endorsed him for the presidency and prepared to file his nomination with election officials, putting pressure on the Kremlin to allow him to run.
President Vladimir Putin's most formidable foe in all his 18 years in power, Mr Navalny is barred from running because of a criminal conviction that is largely viewed as political retribution.
He could run if he gets a special dispensation or if the conviction is cancelled.
Some 800 Navalny supporters on Sunday gathered for a formal endorsement meeting in a giant marquee on the snow-covered riverside in Moscow.
The endorsement was observed by election authorities. Mr Navalny's representative is to file the papers with the Election Commission later in the same procedure that Mr Putin, who is also running as an independent, should follow.
Even though Russian law requires a candidate to submit an endorsement from just 500 people before he or she is allowed to collect the 1 million signatures required to get a place on the ballot paper, Mr Navalny's supporters put on a show of strength on Sunday.
Outdoors endorsement gatherings took place in 19 other cities as well, from Vladivostok to St Petersburg.
Polling agencies show 80% support for Putin, which almost certainly guarantees him a win, but Mr Navalny has managed to galvanise some of Russia's sleepiest regions with a year-long grass-roots campaign.
"We have seen for ourselves this year that overwhelming support for authorities simply isn't there," Mr Navalny told the gathering, flanked by his wife and children, in a campaign speech.
Although election officials are expected to accept Mr Navalny's filing on Sunday, it is highly unlikely that they will let him on the ballot.
Mr Navalny said on Sunday he is confident he will win if he runs, and called on his supporters to boycott the vote if the authorities refuse to register him.
"We are not going to recognise this election but we're not going to step aside either - there will be an all-Russian strike of voters," he said.