Russia's Central Election Commission has officially barred Aleksei Navalny from running against President Vladimir Putin, prompting calls from the anticorruption activist and opposition politician for a boycott of next year's vote.
The commission rejected Navalny's bid to run in the election, saying he was ineligible because of a past criminal conviction.
The commission said the conviction, for which Navalny received a suspended sentence and which he has repeatedly described as politically-motivated, meant he could not run for president.
Polls show Putin is on course to be comfortably reelected, meaning he could remain in power until 2024.
Twelve of the 13-member commission voted on December 25 to bar Navalny. One member of the commission abstained, citing a possible conflict of interest.
In a pre-recorded video message released minutes after the commission announced its decision on December 25, Navalny called on his supporters to boycott the vote.
"The procedure that we're invited to participate in is not an election," he said. "Only Putin and his hand-picked candidates are taking part in it."
"Going to the polls right now is to vote for lies and corruption."
"We are declaring a strike by voters. We will ask everyone to boycott these elections. We will not recognize the result," Navalny said.
Navalny told journalists after the ruling that he would appeal the decision at Russia's Constitutional Court, but that he realized his chances of overturning it were slim.
"Of course, we will appeal it everywhere -- at the Constitutional Court. But we are perfectly aware that it is part of one system," he told journalists.
"It appeared to me that the commission and [its President Ella] Pamfilova personally didn't even try to make it look like their decision was not politically motivated."
Navalny pointed out earlier in front of the commission that his conviction was deemed unfair in the European Court of Human Rights, and that banning him from participation would make the election illegitimate.
"I assure you, a huge amount of people will not go to this election, would actively boycott this election" and hold "electoral strikes," he said.
Navalny told the commission that their decision to bar him would be a vote "not against me, but against 16,000 people who have nominated me, against 200,000 volunteers who have been canvassing for me."
Navalny, 41, on December 24 submitted documents to the CEC that were required for registering as a presidential candidate after announcing he had gathered enough endorsements to run in the election.
"An election without us is not an election," Navalny declared before submitting the papers.
"We are capable of opposing the current authorities. Our key demand is to be allowed to take part in the elections," he told reporters as he was leaving the commission building in central Moscow.
The election commission had already previously ruled Navalny ineligible to run for public office until about 2028 because of a financial-crimes conviction that he says was fabricated by authorities for political reasons.
Navalny was first sentenced in 2013 on embezzlement charges, which accused him of defrauding the budget of Russia's Kirov region of some $270,000.
The European Court of Human Rights last year denounced the ruling, declaring it "arbitrary and manifestly unreasonable." Russia's Supreme Court ordered a retrial, which however gave Navalny the exact same sentence as before, using almost identical wording as the 2013 decision.
On December 24, Navalny's supporters organized rallies in 20 cities across Russia to secure what they said were 15,000 signatures for his candidacy.
At a Moscow rally, he branded Russian leader Vladimir Putin a "bad president."
"It's you, Vladimir Putin, that turned our country into a source of personal enrichment for yourself, your family, and your friends. Therefore, you should no longer be president," Navalny said.
About 800 Navalny supporters gathered for a formal endorsement meeting in a giant tent on the snow-covered riverside in Moscow, with 742 giving him their signature.
According to the law, Navalny needed 500 endorsements in each of 20 cities across the country, his campaign said.
Similar events took place in 19 other cities, including St. Petersburg, Vladivostok, Novosibirsk, Perm, Omsk, Krasnoyarsk, and Yekaterinburg.
"There is no large-scale support for Putin and his rule in this country," Navalny told the meeting. He threatened a boycott of the vote by his supporters if he is barred from running.
Navalny published his full election manifesto last week, focusing on fighting corruption and channeling more money into education and health care. He has also called for a windfall tax on oligarchs and huge cuts to Russia's bloated bureaucracy.
Putin announced his decision to run for a fourth term on December 6. His high approval ratings and control over the levers of power make his victory a foregone conclusion in Russia, where government critics say election campaigns and results are manipulated by the authorities.
Analysts say Putin is eager to score a strong win in a vote with a high turnout in order to make his mandate as strong as possible in what could be his final six-year term, as the constitution bars presidents from serving more than two consecutive terms.
Other candidates have also filed with the commission to run in the election, although critics have accused the Kremlin of sanctioning some opponents merely to give the appearance of a democratic process.
On December 24, one potential opponent, Sergei Mironov from the A Just Russia party, said his party had decided to support Putin and not propose its own candidate.
Ksenia Sobchak, a television personality -- whose late father was Putin's mentor in the early 1990s -- is also planning to run.
Sobchak criticized Navalny's call for boycotting the vote, saying on December 25 that the "election is the only way to change something, and boycotting them is inefficient and harmful."
She proposed that Navalny join her campaign if she gets registered for the race.
Other veterans of past elections, such as liberal Grigory Yavlinsky and ultranationalist Vladimir Zhirinovsky are also running.
The Communists nominated a new candidate, Pavel Grudinin, director of a big strawberry farm just outside Moscow, instead of longtime party chief Gennady Zyuganov.
With reporting by AFP, AP, and the BBC