1 of 3
Misha Japaridze, Associated Press
A communist party supporter shouts anti government slogans during a rally protesting alleged vote rigging in Russia's elections after they visited the mausoleum of Lenin to mark the 88th anniversary of his death at Moscow's Red Square, Russia, Saturday, Jan. 21, 2012.

MOSCOW — Election officials have refused so far to allow the leader of Russia's leading liberal party to compete in March's presidential election, a move the politician said reflects the government's fear of genuine competition.

Grigory Yavlinsky, the leader of Yabloko party, said authorities want to prevent him from challenging Prime Minister Vladimir Putin's bid to extend his 12-year rule by reclaiming the presidency. He said other contenders are only nominal rivals who are following the Kremlin's guidance.

"They aren't letting me join the race, because they don't want to allow an alternative — political, economic and moral," Yavlinsky said at a news conference.

The Central Election Commission said Monday that more than 20 percent of the signatures collected in support of Yavlinsky's candidacy were found to be invalid. It said it would make the final decision on Yavlinsky's candidacy after checking another sample of the more than 2 million signatures required by law for a candidate to qualify.

Massive protests against vote-rigging that favored Putin's party erupted after December's parliamentary election, drawing tens of thousands into the streets in the largest show of public anger since the 1991 collapse of the Soviet Union.

The protests have posed a surprise challenge to Putin's plan of easing back into the presidency, a post he held from 2000-2008.

Yavlinsky's party, which failed to clear a 7-percent threshold required to win seats in parliament, fielded thousands of election observers, who documented evidence of official fraud in favor of Putin's United Russia party in December's vote.

Under the law, observers at the polls can only be named by participants in the race. Yavlinsky charged that a decision to bar him from running also was rooted in authorities' reluctance to allow strong monitoring of the March 4 presidential vote.

The election commission already has registered Putin and three other contenders: Communist Party chief Gennady Zyuganov, ultranationalist Vladimir Zhirinovsky and socialist Just Russia leader Sergei Mironov. Since their parties are represented in the parliament, their registration is easier than for other potential candidates.

Election officials also signaled Monday they would register billionaire tycoon Mikhail Prokhorov, saying that a preliminary check of lists of signatures in his support had shown they correspond to legal norms. Prokhorov owns 80 percent of the New Jersey Nets basketball team.

Yavlinsky said all these candidates represent "different faces of the government" and warned that the refusal to allow him to join the race would undermine the vote's legitimacy and could foment unrest.

"The refusal to allow an alternative — a choice — would erode trust in the vote and deal a blow to its legitimacy," he said. "The less trust and legitimacy are there, the more unpredictable and violent the situation in the country will be."

Putin has tried to play down the massive protests against his rule, casting their leaders as Western stooges. He also has sought to portray himself as the indispensable leader who will guarantee his nation's stability, warning that his radical opponents could push Russia into chaos and violence.

Polls show that Putin continues to enjoy a strong public support, but probably not enough to win a first-round victory. Putin needs to win more than 50 percent of the vote to avoid a runoff.

Putin has refused to take part in televised debates with other contenders, relying instead on ample coverage of his daily activities as prime minister by state-controlled nationwide television stations. He also has published articles outlining his election platform.

An article published Monday in the daily Nezavisimaya Gazeta outlined Putin's views on ethnic issues. Putin suggested, among other things, that Russia should toughen registration rules for migrant workers.

That proposal is likely to please Russian nationalists, who have voiced growing resentment over the influx into Moscow and other cities of dark-skinned Muslim migrants from other ex-Soviet nations and Russia's own North Caucasus region.