MOSCOW - Russia's ruling party on Saturday approved Prime Minister Dmitry Medvedev as its new chief in a bid to reverse flagging popularity that stoked opposition protests against the Kremlin. A United Russia congress in Moscow overwhelmingly confirmed by a show of hands Medvedev's candidacy to take over from President Vladimir Putin as party leader, with no apparent opposition and no other candidate contesting the post. Medvedev's move to become a card-carrying party leader is a key plank in Russia's new power structure that saw him cede the Kremlin to Putin earlier this month after serving four years as president.

In a highly-orchestrated event, Putin formally announced Medvedev's candidacy at the central Manezh hall next to the Kremlin to a crowd of 3,000 guests and delegates.

"I consider United Russia my key ally and partner," said Putin, dispelling speculation that the party has been sidelined by the Kremlin and could even be disbanded after it lost support in December parliamentary elections.

Putin has been the leader of the party since 2007, although curiously never joined. He decided to fully step aside in April after announcing that leading the party is inappropriate for the president.

Medvedev - who previously criticised United Russia and compared it to political stagnation of the Soviet Union's Brezhnev era - this week formally joined the party and vowed to reform it from the inside.