Russian opposition Yabloko party founder Grigory Yavlinsky could be denied registration as a presidential candidate by Russia’s Central Election Commission.
The Interfax news agency cited election commission member Yelena Dubrovina, who represents Yabloko, as saying that about 10 percent of Yavlinsky's signatures have been declared invalid.
Russian law on presidential elections requires would-be candidates to provide at least 2 million valid signatures in order to be registered.
Yavlinsky has submitted 2,132,000 signatures.
Earlier, unconfirmed reports indicated that as many as 26 percent of Yavlinsky's signatures had been rejected.
Speaking to reporters in Moscow on January 23, Yavlinsky insisted he is being barred because of his opposition positions.
"This issue is of a political nature, absolutely, and the purpose of [denying registration] is to bar from elections all those people who are discontent with what is happening in Russia today and who would like a different future for Russia -- an open, democratic, European, modern future," Yavlinsky said.
He added that Yabloko plans to register hundreds or even thousands of observers for the election and that is also a reason the Kremlin might refuse to register him.
"This decision is strictly political and it has nothing to do with the signatures or their quality," he said.
Yabloko party official Sergei Ivanenko told RFE/RL that all Yavlinsky's signatures are valid -- even though officials gave only 20 days for would-be candidates to collect the necessary 2 million.
The application of another would-be candidate, Irkutsk Oblast Governor Dmitry Mezentsev, is also reportedly in danger. Dubrovina said that 10 percent of his signatures were also rejected.
Dubrovina said the election commission will begin a second evaluation of the signatures, and that both candidates could still be registered. The results should be made official in the next three days, she said.
Billionaire Mikhail Prokhorov's registration seems to be assured. Dubrovina said that less than 5 percent of his submissions were invalidated. On his blog, Prokhorov expressed concern about Yavlinsky's possible disqualification, saying: "I want to participate in an honest, competitive election."
Russia's presidential election is scheduled for March 4, and Prime Minister Vladimir Putin is seeking a third presidential term.