MOSCOW - Russian Prime Minister Vladimir Putin's ruling United Russia party begins a two-day congress on Friday that will be scrutinised for clues to who will run for president next March: Putin or his protege, President Dmitry Medvedev.

United Russia is due to set out its strategies and select candidates for the December 4 parliamentary election, in which it may struggle to maintain its two-thirds majority in the State Duma, Russia's lower house.  

That vote will in turn set the stage for the presidential election. Some political analysts think Putin will see how United Russia performs in December before announcing who will run for the top office.

Putin, 58, who served as president for the maximum two straight terms from 2000-2008, then steered Medvedev into the Kremlin, is free to run again, and has said he may do so.

Medvedev, 46, has also said he may seek re-election but has indicated they will not run against one another. Supporters have urged him to announce his candidacy, but some already see him as a lame duck eclipsed by an increasingly active and dominant Putin.  

However, a poor performance by United Russia in December could signal that Putin's conservative policy is losing support, and prompt him to give the younger and more liberal Medvedev a second chance.  

A VTsIOM opinion poll in July had United Russia narrowly losing its two-thirds majority, securing 291 of 450 seats in the lower house.  

Both men will make addresses on Saturday in an arena at Moscow's Luzhniki sports complex.

Putin, the party chairman, will speak for an hour. Medvedev, who has no political party as a power base, has 20 minutes.  

Campaign trick

"The party urgently needs a campaign trick, something that will attract voters," said political analyst Pavel Salin.

He said Putin and Medvedev were unlikely to announce their presidential plans before December, but could make a splash with a spending initiative or a piece of political reform -- such as giving more powers to the Duma at the expense of the president.

Despite a string of public appearances that to many look like campaign outings, Putin has asked his party to avoid speculation about the presidency and focus on the parliamentary election, in which he wants it to retain the two-thirds majority that enables it to change the constitution.

"The work will be hard. United Russia ... is burdened by certain problems from the past and issues unresolved by authorities," he said in a speech ahead of the congress.  

Worried by his party's flagging approval ratings and its showings in regional elections, Putin in May launched an umbrella group called the All-Russia People's Front in a bid to broaden support.  

Activists from the People's Front will occupy 185 out of 600 places on the United Russia's parliamentary candidate lists, and speculation is growing that Medvedev might also be included.  

United Russia's main rivals are the Communist Party and flamboyant nationalist Vladimir Zhirinovsky's LDPR, which supports the majority of government initiatives in the Duma.  

Just Russia, the only other party with seats in the current Duma, suffered a blow when United Russia ousted its leader from the post of upper parliament house speaker in May.