A bill extending the Russian presidential term from four to six years moved quickly Wednesday toward parliamentary approval, an effort some observers say could pave the way for Vladimir Putin's return to the presidency.

Russian lawmakers approved the second of three readings of a bill to extend the presidential term from four to six years. The final reading in the Kremlin-controlled State Duma is set for Friday, after which the bill will go to the upper house where a swift approval is also expected.

The Duma voted 351-57 on Wednesday to quickly pass the bill, which was proposed by President Dmitry Medvedev.

Only the Communists voted against the legislation.

The second reading provoked loud disputes in the usually sedate lower house, with one Communist lawmaker proposing an amendment limiting presidents to just one term, while pro-Kremlin nationalist party leader Vladimir Zhirinovsky proposed extending the presidential term to seven years instead of six.

Both amendments were ignored by the head of the constitutional affairs committee, Vladimir Pligin of the main Kremlin-directed United Russia party, who argued that the current law does not allow individual lawmakers to offer changes in the constitution.

The widely popular Putin, now prime minister, was barred constitutionally from seeking a third consecutive term as president in elections this year. His protege Medvedev resoundingly won the post in March.

If enacted, the change would not apply to Medvedev's current term, due to end in 2012.

Putin has said the term extension was not tailored for him and would help boost Russia's democracy, but many observers say that Medvedev could step down early so that Putin can reclaim the presidential seat.