( dpa ) - Russia's former prime minister Mikhail Kasyanov was the last of five candidates to file paperwork to Russia's election committee by Wednesday's deadline for the March presidential vote.
Supporters of the opposition candidate were scrambling to collect a required two million signatures during Russia's long holidays from January 1 to a second Julian calender new year 13 days later.
The only hurdle left for Kasyanov is whether the Central Elections Commission (CEC) will approve his registration.
On Wednesday the CEC announced it would take ten days for a panel of experts to review the 2.07 million signatures, weighing 2 tons, news agency Interfax reported. Five per cent of "fraud" will disqualify Kremlin critic.
"If registered, I shall not withdraw from the race under any circumstance," he said.
Addressing supporters he promised: "We shall go to the bitter end."
Some observers believe that Kasyanov's registration will be rejected on technical grounds if the Kremlin decides against his running.
If successful, Kasyanov will be the only opposition figure from the activist anti-Kremlin political movement that organized a series of so-called Dissenters' Marches in the run-up to December parliamentary elections.
Former chess hero Garry Kasparov pulled out of the race in December saying he was blocked by authorities from holding a congress for his nomination.
The only other candidate looking to join the ballot by collecting signatures was the head of the Democratic Party of Russia Andrei Bogdanov, who submitted 2.1 million signatures Wednesday.
Critics pointed out that the party received less than 90,000 votes in last month's State Duma election, alleging the party is part of a Kremlin project to divide the opposition.
The candidate backed by President Vladimir Putin in December, First Deputy Prime Minister Dmitry Medvedev, is exempt from submitting signatures because he was nominated by two parties in parliament: United Russia and A Just Russia.
Fielded by their parties, the two other candidates, Communist leader Gennady Zyuganov and Vladimir Zhirinovsky, head of the ultranationalist Liberal Democratic Party are also spared the signature requirement.
There is no minimum turnout for the election validity, but the CEC has launched a large campaign to get out the vote, which critics charge is motivated by the Kremlin's desire for a landslide win guarantee for edvedev, widely seen as the candidate of continuity.
According to a recent poll by the independent Moscow-based Levada Canter, 80 per cent of voters are confident that he will continue "Putin's policies."
Putin's soaring popularity ratings of over 70 per cent seem to have transferred to his anointed successor with Medvedev's ratings climbing with every poll.