Russian billionaire Mikhail Prokhorov warms up during a basketball training session in a secondary school in Moscow on February 16, 2012. Russian metals tycoon and US basketball team owner Prokhorov challenges Prime Minister Vladimir Putin in the March 2012 presidential polls. AFP PHOTO/KIRILL KUDRYAVTSEV

Russian billionaire Mikhail Prokhorov warms up during a basketball training session in a secondary school in Moscow on February 16, 2012. Russian metals tycoon and US basketball team owner Prokhorov challenges Prime Minister Vladimir Putin in the March 2012 presidential polls. AFP PHOTO/KIRILL KUDRYAVTSEV

Russian billionaire Mikhail Prokhorov warms up during a basketball training session in a secondary school in Moscow on February 16, 2012. Russian metals tycoon and US basketball team owner Prokhorov challenges Prime Minister Vladimir Putin in the March 2012 presidential polls. AFP PHOTO/KIRILL KUDRYAVTSEV

Russian billionaire Mikhail Prokhorov speaks at a basketball training session at a secondary school in Moscow on February 16, 2012. Prokhorov, who hopes to challenge Vladimir Putin for the presidency, is officially registered to run, becoming the fifth candidate in the historic March race. AFP PHOTO/KIRILL KUDRYAVTSEV

Russian billionaire Mikhail Prokhorov attends a basketball training session at a secondary school in Moscow on February 16, 2012. Prokhorov, who hopes to challenge Vladimir Putin for the presidency, is officially registered to run, becoming the fifth candidate in the historic March race. AFP PHOTO/KIRILL KUDRYAVTSEV

Russian billionaire Mikhail Prokhorov wipes his forehead during a basketball training session at a secondary school in Moscow on February 16, 2012. Prokhorov, who hopes to challenge Vladimir Putin for the presidency, is officially registered to run, becoming the fifth candidate in the historic March race. AFP PHOTO/KIRILL KUDRYAVTSEV

Russian billionaire Mikhail Prokhorov does push ups on basketballs at a basketball training session at a secondary school in Moscow on February 16, 2012. Prokhorov, who hopes to challenge Vladimir Putin for the presidency, is officially registered to run, becoming the fifth candidate in the historic March race. AFP PHOTO/KIRILL KUDRYAVTSEV

Russian billionaire Mikhail Prokhorov attends a basketball training session at a secondary school in Moscow on February 16, 2012. Prokhorov, who hopes to challenge Vladimir Putin for the presidency, is officially registered to run, becoming the fifth candidate in the historic March race. AFP PHOTO/KIRILL KUDRYAVTSEV

Russian billionaire and presidential candidate Mikhail Prokhorov has a basketball training session with students of a Moscow secondary school in Moscow, Thursday, Feb., 16, 2012. (AP Photo/Sergey Ponomarev)

Russian billionaire and presidential candidate Mikhail Prokhorov at a basketball training session with students of a Moscow secondary school in Moscow, Thursday, Feb., 16, 2012. (AP Photo/Sergey Ponomarev)

Russian billionaire and presidential candidate Mikhail Prokhorov signs autographs at his meeting with young people in the Black Sea resort of Sochi, southern Russia, Wednesday, Feb. 8, 2012. Prokhorov is running for president on March 4 election. (AP Photo/Igor Yakunin)

A couple shares a tender moment near an election billboard of billionaire Mikhail Prokhorov with his photo in St.Petersburg, on January 12, 2012. The presidential voting in Russia is scheduled on March 4, 2012. AFP PHOTO / OLGA MALTSEVA

Members of Russian billionaire Mikhail Prokhorov's election campaign team talk to passers-by as they collect supporters' signatures, two million of which are necessary for the registration of the presidential candidate, in St.Petersburg, Russia, Thursday, Jan. 12, 2012, with an election poster depicting Mikhail Prokhorov covered with rain drops on the right. The Russian presidential elections are scheduled for March 2012. (AP Photo/Dmitry Lovetsky)

A member of Russian billionaire Mikhail Prokhorov's election campaign, left, collects supporters' signatures, two million of which are necessary for the registration of the presidential candidate, by an election poster depicting Mikhail Prokhorov in St.Petersburg, Russia, Thursday, Jan. 12, 2012. The Russian presidential elections are scheduled for March 2012. (AP Photo/Dmitry Lovetsky)

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. Prokhorov said he will challenge Prime Minister Vladimir Putin in next March's presidential election. While he was cautious not to cross Putin's path in the past, Prokhorov may pose a serious challenge to Putin, whose authority has been dented by the Dec. 4 parliamentary election and massive protests against vote fraud. (AP Photo/Misha Japaridze)

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. (AP Photo/Misha Japaridze)

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.(AP Photo/Misha Japaridze)

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. (AP Photo/Misha Japaridze)