In a campaign statement in the Russian daily Vedomosti that barely mentioned Putin and focused instead on public dissatisfaction with Russian politics, she said that she was "outside of ideology" and not a fan of Russia's annexation of Crimea (though she denied being against it).
"I am 'against all,' " she wrote, announcing her candidacy. "You are not for Sobchak, you are voting against all - against Yavlinsky, Zyuganov, and Putin." The first two refer to opposition candidates Grigory Yavlinsky and Gennady Zyuganov. Putin, who has not announced his candidacy despite the elections being less than six months off, has been president or prime minister of Russia since 1999.
In the past six months, Russia has seen a rise in protest sentiment among young people in high school and college, and the government is looking to channel that anger into a safe political movement. Those young protesters were largely inspired by the anti-corruption whistleblower and protest leader Alexei Navalny, who has been disqualified from running by multiple felony charges that he claims are politically motivated.
Sobchak announced her candidacy on the independent TV Rain channel. Half an hour earlier, Dmitry Peskov, Putin's personal spokesman, told the channel that her candidacy was seen as legitimate by the Kremlin.
"If I understand correctly, Ksenia fully falls under the provision of our Constitution," he said. "She is a Russian citizen who, according to the Constitution, may run for president, naturally, after the completion of all necessary procedures and formalities, which are also spelt out in our laws."
The New Times, a liberal Moscow weekly that reported her candidacy several hours before it became official Wednesday, suggested that Sobchak was hoping to break back onto federal television channels, where she had made her name before being banned because of her political views. Her participation will probably split the protest vote, drawing from Navalny supporters, the magazine said.
Sobchak is the daughter of Anatoly Sobchak, the former St. Petersburg mayor who hired a young Putin as his deputy mayor in the tumultuous 1990s. It has been rumored, though never confirmed, that Ksenia Sobchak is Putin's goddaughter.
Sobchak's father died in 2000. Her mother, Lydumila Narusova, is a former member of Russia's upper house of parliament. Sobchak, who is not backed by a political party, must collect 300,000 signatures to register as an independent candidate. She has an Instagram account with 5.2 million followers and is a regular guest at black-tie events.
Putin has not said that he plans to step down. He has been in power since New Year's Eve 1999, when President Boris Yeltsin announced he was stepping down. Putin, who has shuffled between the presidency and the role of prime minister, has been in power for more than 6,630 days, a month longer than former Soviet leader Leonid Brezhnev's 6,601 days in office.
A powerful oligarch, Mikhail Prokhorov, stepped in as a liberal candidate during the 2012 presidential elections, when he captured 8 percent of the vote as an independent. Some thought his candidacy was welcomed by the Kremlin, making Putin's inevitable victory appear more legitimate. Despite taking third place in those elections, Prokhorov has since exited politics. Other candidates have run consistently since 1996 with little success. Putin has regularly won more than 60 percent of the vote and often more than 70 percent.
Sobchak spoke during the 2011 and 2012 "white ribbon" protests against Putin, which brought 100,000 people onto the streets in protest of alleged vote rigging and Putin's return to the presidency in 2011. But she has limited her role in politics since then, largely focusing on a television show on the independent (and often opposition) channel TV Rain, while working on other private projects.
She first gained fame for her role on the Russian "Big Brother" takeoff "Dom-2," or "House-2," where contestants from across Russia live in a house together and viewers can watch their daily lives.