Prime Minister Vladimir Putin of Russia says he has accepted a proposal to stand for president next year.
Addressing the annual congress of the ruling United Russia Party, Mr Putin and President Dmitry Medvedev backed one another to switch roles.
The BBC reports the announcements end speculation over which man would run for president.
The party dominates Russian politics and Mr Putin's return to the Kremlin is now all but guaranteed.
He previously served two terms as president before Mr Medvedev took over in 2008. Mr Putin was barred by the constitution from running for a third consecutive term.
Earlier, Mr Putin told delegates that Mr Medvedev should head the party's list of candidates in December's parliamentary elections. Mr Medvedev accepted.
Mr Putin also indicated that Mr Medvedev could become prime minister.
He told delegates that they had reached agreement on who should hold which post "a long time ago, several years back".
Correspondents say most Russians believe Mr Putin has greater influence in the country and far more power than Mr Medvedev.
''Bitter medicine'' ahead
Mr Putin also warned of possible, unpopular measures to cope with the global financial turmoil.
''The task of the government is not only to pour honey into a cup, but sometimes to give bitter medicine,'' he said.
''But this should always be done openly and honestly, and then the overwhelming majority of people will understand their government.''