Russian officials said on Friday they found "errors" in a bid by presidential hopeful Boris Nadezhdin to register to challenge Vladimir Putin, paving the way to bar him from the March vote.
Nadezhdin has spent weeks criticising long-term President Putin and the Kremlin's military offensive in Ukraine, which is nearly into its third year.
Nadezhdin, 60, sparked queues all over Russia in January, when supporters submitted signatures so he could be registered as an official candidate in the presidential election.
On Wednesday, he handed in more than the 100,000 required signatures to the Central Election Commission, which is expected to rule next week whether he will be allowed to stand.
"When we see dozens of people who are no longer on this Earth and they add a signature, that poses question about the ethical standards being used... including by the person collecting them," the commission's deputy chairman Nikolay Bulayev said, in reference to Nadezhdin.
He summoned Nadezhdin and another candidate -- Communist Sergei Malinkovich -- to appear on Monday before the commission, where officials would show them the "results of the checking procedure".
Nadezhdin -- who has spent weeks criticising President Putin and the almost two-year Ukraine offensive -- dismissed the commission's accusations.
"We are all more alive than the living," he said, posting photographs on Telegram of people queueing to submit signatures.
He alluded to the Russian literature classic "Dead Souls" to mock election officials.
"If someone sees dead souls in my signature lists, well, friends, these questions should not be addressed to me. It's more for the church or exorcists," he said.
In a post earlier on Friday, Nadezhdin repeated that he would take the election commission to court if it barred him from running.
In an interview to AFP last month, he said Putin's decision to launch the Ukraine offensive in 2022 had been "catastrophic".
Many have been surprised that he has been allowed to progress this far in the voting process.
Political analyst Tatiana Stanovaya said the election commission's comments were a sign Nadezhdin would not be allowed to stand.
"The Kremlin has started to prepare the public for the decision of barring Nadezhdin," she said on Telegram.
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