Russia's Prime Minister Dmitry Medvedev speaks during the United Russia Party's congress in Moscow, capital of Russia, on May 26, 2012. Russia's ruling United Russia party elected Prime Minister Dmitry Medvedev as its new leader Saturday. [Xinhua]

Russian Prime Minister Dmitry Medvedev on Saturday succeeded President Vladimir Putin as leader of the ruling United Russia party.

Medvedev's appointment was overwhelmingly approved at the party's congress here by a show of hands.

Accepting the post, Medvedev vowed to improve the United Russia and lead the party to more victories.

On the next parliamentary elections due in 2016, Medvedev stressed that the United Russia "must be at the top again and win a parliamentary majority."

If the party wins the parliamentary elections, State Duma speaker candidates could be selected on a competitive basis, Medvedev said.

"In the future parliamentary election, the United Russia will again try to win the support of the majority of citizens. And if we fulfill this task, and I don't doubt we will, it would be right to consider the issue of our candidates to the leadership in the State Duma, in particular the post of Duma chairman, in a democratic, open way, and on an alternative basis," the new party leader said.

Besides, Medvedev said that it is necessary to reform the ways of electing party leaders at all levels, set a single five-year term of office for party leaders at all levels, and introduce the principles of annual performance reporting and annual rotation.

These proposals were adopted in the new party constitution approved during the congress.

Putin, who had led the party since 2008, told the congress that "it is correct that Dmitry Medvedev becomes the leader of the United Russia."

He urged the party to continue the efforts to remain "a party of popular majority."

"The United Russia and all of us should work diligently in future, to fulfill all given promises, to be honest, to listen to the people and to respond immediately to problems," Putin said.

"Leadership should be proven and confirmed every day with practical work," he stressed.

The Russian president also noted that political competition in the country will increase, which is a good thing.

"I believe that this will give impetus to the country's development, as well as improve maturity and responsibility of our civil society," Putin said.

Although he had served as the leader of the United Russia, Putin never formally joined the party.

In late April, Putin said he would quit as chairman of the party, and nominated Medvedev as his successor.

He said that although the Russian constitution does not prohibit the president from being a party member, the spirit is that the president is a consolidating figure for all political forces and for all citizens.

Medvedev, the former Russian president, accepted Putin's nomination and joined the party on Tuesday.

Also during the party congress, Boris Gryzlov was reelected chairman of the United Russia's Supreme Council.

Gryzlov has been head of the Council since November 2002.

Founded in 2001, the United Russia is a dominant party in the country with more than 2 million members.

In last December's parliamentary elections, the party retained a much-reduced majority, compared with a two-thirds majority in 2007.