Russian President Dmitry Medvedev meets with the Russian Chamber of Commerce and Industry at the Kremlin in Moscow on Tuesday. (Dmitry Astakhov/Associated Press)

President Dmitry Medvedev submitted a bill Tuesday to extend Russia's presidential term from four years to six, making good on a promise in a state of the nation address earlier this month.

Aides say the term change would only apply to future presidents, which puts to rest any possibility of Medvedev getting a lengthened term.

If approved as expected by lawmakers, the lengthy term means that Vladimir Putin, Medvedev's predecessor and the current prime minister, would be eligible for another 12 years in a second presidential stint should he choose to run again.

The widely popular Putin was constitutionally barred from seeking three consecutive terms as president, but faces no restriction on the number of terms he can serve, paving the way for a possible return in the wake of Medvedev's presidency.

Following an eight-year stint as Russia's president, Putin tapped protégé Medvedev as his favoured successor, ensuring his election in May.

Putin then became prime minister, but is still widely seen as the man calling the shots in Russia.

Speculation of shortened Medvedev presidency abounds

Medvedev's swift move to extend the presidential term sparked speculation that Putin might not wait until scheduled elections in 2012 to seek a return to the office.

"It is one of the more legitimate suggestions. Such ideas were around before Putin's own term ended," said Masha Lipman, a political analyst with the Carnegie Moscow Centre.

Business daily Vedomosti quoted an unnamed Kremlin official last week as saying Medvedev might even step down next year, triggering an early ballot to return Putin to the helm.

"There is little doubt that Putin remains the most powerful politician and makes all the major decisions," Lipman said.

She warned, however, that changing the constitution could set a dangerous precedent. Medvedev's bill must be approved by both houses of parliament as well as two-thirds of regional legislatures.

The bill would also extend the term of the lower house of parliament, the State Duma, from four years to five. Medvedev also submitted a separate proposal to give the Duma more control over the cabinet.

That change could also play into Putin's hands, as he leads the United Russia party, which dominates the Duma and politics nationwide.

Putin last week ordered United Russia lawmakers to ensure that Medvedev's proposals were passed.