MOSCOW (Reuters) - Russian opposition leader Alexei Navalny on Sunday cleared the first hurdle towards taking part in next year’s presidential election, even though the central election commission has previously ruled him ineligible to run.

Navalny, 41, is a fierce opponent of President Vladimir Putin, who is widely expected to win re-election in March, extending 17 years in power.

A veteran campaigner against corruption among Russia’s elite, he won the initial support of 742 people at a gathering in a district of Moscow - above the minimum 500 required to initiate a presidential bid.

“There is no large-scale support for Putin and his rule in this country,” Navalny told the meeting, describing himself as a “real candidate” for election and threatening a boycott of the vote by his supporters if he is barred from running.

On Sunday evening, Navalny submitted the documents to the central election commission needed to be registered as a candidate.

The commission, which extended its working hours on Sunday to take the documents, has five days in which to decide whether Navalny will be registered.

The commission has previously said he is ineligible due to a suspended prison sentence that he says was politically motivated.

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“We are capable of opposing the current authorities. Our key demand is to be allowed to take part in the elections,” Navalny told reporters as he was leaving the election commission building in the central Moscow.

Navalny has been jailed three times this year on charges of repeatedly organizing public meetings and rallies in violation of existing laws.

The European Court of Human Rights ruled in October that Navalny’s conviction for fraud in 2014 was “arbitrary” and ordered Moscow to pay him compensation.

The ruling party United Russia meeting on Saturday pledged “all possible support” to the 65-year-old Putin in his bid to win a further six years in power in the March election.

The Communist Party, which came second after United Russia in a parliamentary election last year, named Pavel Grudinin, 57, as its candidate, dropping veteran party leader Gennady Zyuganov.

Another politician who has run before, Sergei Mironov from A Just Russia party, said his party had decided to support Putin instead and not propose its own candidate.

Property developer Sergei Polonsky, who has been convicted of defrauding investors, also secured enough initial backing to seek clearance from the election commission to take part in the presidential race.

Others planning to run include television personality Ksenia Sobchak, whose late father was Putin’s boss in the early 1990s, journalist Ekaterina Gordon.