The Moscow election commission said Thursday it would consider disqualifying Alexei Navalny from next month's race for city mayor as support for President Vladimir Putin's top critic climbed on the back of a vigorous campaign.
The commission will meet "soon" to discuss violations in the campaign of the leader of the country's protest movement, its chief Valentin Gorbunov said.
"If the violations exceed the norms established by the law than the question will be raised of cancelling the registration of the candidate," Gorbunov said in comments confirmed to AFP by a spokesman.
The election commission later said, citing "multiple" voters' reports, that the violations included the distribution of campaign literature.
Navalny, who is campaigning under the shadow of a five-year prison term on embezzlement charges, indicated he believed that the authorities made the move because they feared he could score embarrassingly well in the September 8 vote.
"Oi! The Moscow election commission announced that I could be removed from the polls," Navalny said in a message on Twitter.
"Just when the run-off had become inevitable, and SUDDENLY..."
"Opinion polls show that I have every chance to get into a second round and win," Navalny added on Echo of Moscow radio. "They will do everything to stop this scenario."
Pro-Kremlin Moscow mayor Sergei Sobyanin is widely expected to win the poll but Navalny has vowed to force it into a runoff, which would happen if Sobyanin failed to win 50 percent of votes in the first round.
Nearly 20 percent of Muscovites who have already decided on their candidate would vote for Navalny, according to Synovate Comcon, a market research agency. More than 63 percent would vote for Sobyanin.
Pro-Kremlin VTsIOm pollster puts election ratings for Navalny at 13-15 percent.
Support for Navalny has risen from s ingle digits just a month ago as Navalny launched a robust Western-style campaign complete with fiery stump speeches and eye-catching paraphernalia.
He was allowed to run for mayor in a hugely surprising move after a court sentenced him to five years in prison last month for embezzlement in a disputed verdict.
He was arrested in the courtroom but then in an unprecedented development released pending his appeal in a move the authorities said would allow him to campaign.
Gleb Pavlovsky, a political analyst and one-time Kremlin insider, said that while the prospect of a run-off was highly unlikely, the growing support for Navalny made the authorities uncomfortable.
"The authorities will have to choose the lesser of two evils," Pavlovsky told AFP. "Removing Navalny from the polls would lead to a scandal. Allowing Navalny to run is also unacceptable."
"Navalny will be removed from the race if his approval ratings reached critical figures," he added.
It remains unclear whether Navalny will have enough time to actually participate in the ballot.
A confirmation of the guilty verdict against Navalny would disqualify him from politics, a restriction that will come into force if or when the ruling is upheld on appeal.
Police said last week they had raided a Moscow apartment acting on a tip that it contained illegal campaign materials supporting Navalny.
The raid took place in the presence of Nikolai Levichev, a rival candidate from the Kremlin-friendly A Just Russia party.
Navalny said Thursday that the authorities raided one of the two printing houses that publishes leaflets for his campaign.
Earlier this month, Russian prosecutors accused Navalny, a 37-year-old father of two, of breaking the law by receiving donations from foreign nationals.
The charismatic lawyer who rose to fame during anti-Putin rallies that broke out in Moscow in the winter of 2011, denied the claim and said that all the funding for the mayoral race was being gathered in strict accordance with the law.