Prime Minister Vladimir Putin will run for president in March elections, while the junior member of the ruling tandem, incumbent President Dmitry Medvedev, will head United Russia's State Duma list and likely take over as prime minister.
Medvedev announced Putin's bid at a United Russia party congress in Moscow on Saturday. His request that the congress back his mentor was met with a standing ovation.
"I am ready to continue my work of modernizing the country from within the government," Medvedev said. "It will be a radically revamped government."
Putin said at the congress that the decision had been made "several years ago." For years, the ruling tandem had been stubbornly dodging questions about who will run in 2012.
Putin confirmed that if he wins, he will appoint Medvedev prime minister, provided that United Russia is victorious in December.
Putin served two terms as president between 2000 and 2008, when he stepped down, citing a constitutional restriction on additional consecutive terms. He chose his longtime aide and ally Medvedev as his successor and took up the prime minister's job after the 2008 vote.
Many analysts said at the time that Medvedev was being used as a placeholder to comply with the Constitution, which permits more than two non-consecutive terms.
Putin, who heads United Russia but is not a member, topped the party's list for the last Duma vote in 2007, a position Medvedev will fill in December elections, which the ruling party is poised to win, though perhaps not as convincingly as it did four years ago.
The presidential term was extended from four to six years in 2008, which means Putin, 58, can now stay in power until 2024, when he will be 70.