MOSCOW — More than 15,000 Russians on Sunday endorsed the candidacy of Alexei Navalny, seen as the only Russian opposition leader who stands a fighting chance of challenging President Vladimir Putin in a March vote.

"An election without us is not an election," Navalny declared in Moscow around 1700 GMT before submitting his nomination to the Central Electoral Commission, which will rule whether he can run.

Authorities have deemed the 41-year-old ineligible to run due to a criminal conviction, saying "only a miracle" would help him get registered. Navalny has described the conviction as politically motivated.

Thousands backing the charismatic lawyer met in 20 cities from the Pacific port of Vladivostok to Saint Petersburg in the northwest to nominate him as a candidate in the presence of electoral officials to boost his chances of contesting the March 18 ballot.

His campaign said more than 15,000 people endorsed him nationwide. An independent candidate needs 500 votes to get registered with election authorities, according to leglisation.

In Moscow, more than 700 people supported Navalny’s candidacy as they gathered in a huge marquee set up in a picturesque park on the snow-covered banks of the Moscow River.

"I am hugely happy, I am proud to tell you that I stand here as a candidate of the entire Russia," the Western-educated Navalny told supporters earlier.

"We are ready to win and we will win these elections," Navalny said before finishing his speech in a cloud of confetti.

Navalny said that if he is not allowed to put his name on the ballot he will contest the ban in courts and repeated his threat to call for the polls to be boycotted if he did not get registered.

"Thwart the elections if they are dishonest," he told supporters.

Putin, 65, announced this month that he will seek a fourth presidential term, which would extend his rule until 2024 and make him the longest-serving Russian leader since Communist leader Joseph Stalin.

He is widely expected to sail to victory.

But with the result of the March vote a foregone conclusion, turnout could be low, harming Putin’s hopes for a clear new mandate, observers say.

Navalny, who has tapped into the anger of a younger generation who yearn for change, hopes that popular support for his Kremlin bid would pressure authorities into putting his name on the ballot.

"If Navalny is not allowed to run, I am not going to vote," pensioner Marina Kurbatskaya said in Moscow. "I don’t see anyone else who I want to become president." — AFP