Misha Japaridze, Associated Press
Mikhail Prokhorov, one of Russia's richest tycoons and New Jersey Nets basketball team owner, speaks at a press conference in Moscow, Russia, Monday, Dec. 12, 2011, as he announces his candidacy to run against Russian Prime Minister Vladimir Putin in the March 2012 presidential election. Prolhorov has been cautious not to cross Putin's path in the past, but may pose a serious challenge to Putin, whose authority has been dented by the Dec. 4 parliamentary election and recent massive street protests against alleged vote fraud.

MOSCOW — The Russian billionaire who plans to challenge Vladimir Putin in Russia's presidential election said Thursday that his first move if elected will be to pardon jailed tycoon Mikhail Khodorkovsky.

Mikhail Prokhorov said he would also allow free registration of opposition parties and restore popular elections of provincial governors if he wins March's vote. Putin has marginalized the opposition forces, tightened election rules and abolished direct elections of governors during his 12-year rule.

Prokhorov, estimated to be worth $18 billion, made his fortune in metals, banking and media. He also owns 80 percent in the New Jersey Nets. Khodorkovsky, once Russia's richest man, has been in jail since 2003 on tax evasion and fraud charges seen as a punishment for defying Putin's power.

Speaking at a meeting with supporters who nominated him for the race, Prokhorov hailed last weekend's protest in Moscow against vote fraud, which attracted tens of thousands in the largest show of discontent in 20 years.

"I deeply understand the demands and the strivings of the people who took to the streets," Prokhorov told reporters, adding that he may join a follow-up protest later this month.

He said he wasn't afraid to challenge Putin's power. "Putin is a serious rival, but I'm not afraid of competition," he said.

Prokhorov's presidential bid follows his botched performance before the parliamentary election when he formed a liberal political party with the Kremlin's tacit support but abandoned it under what he called Kremlin pressure.

Some observers alleged that Prokhorov may have made amends with the Kremlin and might be running for president to accommodate voters unhappy with the authorities to steal the thunder from the opposition.

Prokhorov said in his blog Wednesday that he would play his own game.

"Naturally, my candidacy is good for the Kremlin. Naturally, they want to play democracy and show that people have 'some kind of a choice'," he wrote.

"But we must absolutely use the authorities, too, if we don't want to just make some noise and disappear, but to change our lives for the better."