President Dmitry Medvedev's suggestion last week triggered speculation that the extension of the current four-year parliamentary and presidential terms, which would apply to the next head of state and legislature, was a pretext to the return to office of his predecessor and now premier, Vladimir Putin.
State Duma Speaker Boris Gryzlov said the debates and votes on the second and final third readings could take place next week.
A member of the United Russia party said the votes could be held on Wednesday
Some senior members of the State Duma dominated by the pro-Kremlin United Russia party said after the announcement earlier this week that the house could approve the amendments in three readings.
Gryzlov also dismissed speculation that the amendments were paving the way for early presidential and parliamentary elections. "Everyone must work to the end of his term," he said.
The constitutional amendments will enter into force once they have been approved by both houses of parliament and at least two-thirds of regional legislatures and published in a government newspaper.
