Prokhorov, whose wealth the Forbes magazine has estimated at $18 billion, has been cautious not to cross Putin's path in the past. But the tycoon's candidacy may now pose a serious challenge to Putin, whose authority has been dented by his party's poor showing in Russia's Dec. 4 parliamentary election and allegations of widespread fraud during the balloting.
Putin's party only won about 50 percent of that vote, compared to 64 percent four years ago, and the fraud allegations have allowed opposition parties to successfully mount massive anti-Putin protests in Russia.
"The society is waking up," Prokhorov said at the news conference he held in Moscow to announce his candidacy. "Those authorities who will fail to establish a dialogue with the society will have to go."
On Sunday, President Dmitry Medvedev promised on his Facebook page that the alleged vote fraud during the parliamentary election will be investigated. But Putin's spokesman, Dmitry Peskov, predicted Monday the probe will show that little vote fraud occurred and that it had no effect on the outcome.
"If you take all the cases of these alleged violations or whatever was published online, the total will be less than 1 percent of the overall number of votes," Peskov told The Associated Press in an interview. "And even hypothetically speaking, if they are all appealed in court, it will in no way affect the legitimacy of the election."
Peskov's comment signaled that Putin — who served as Russia's president in 2000-2008 and only became prime minister because of term limits — is holding firm, despite the protests, which have been the largest here since the 1991 collapse of the Soviet Union. On Saturday, tens of thousands of people in Moscow and smaller numbers in more than 60 other cities protested election fraud and called for an end to Putin's rule.
Prokhorov, 46, said he hopes to win the support of Russia's growing middle class, which formed the core of Saturday's demonstrations. However, he said he agrees with only some of the anti-Putin and anti-government slogans that were shouted out at the rallies. He also did not say whether he plans to attend a follow-up protest in Moscow later this month.
