MOSCOW (Reuters) - Russian President Dmitry Medvedev asked lawmakers on Tuesday to approve a draft law extending the presidential term of office, a change some observers say is part of a plan to bring Vladimir Putin back to the Kremlin.

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Medvedev, who took over the presidency from his mentor Putin this year, proposed extending the term from four to six years in a speech last week and has now submitted a draft law on the change to parliament, the Kremlin said.

Putin is ranked in opinion polls as Russia’s most popular politician and Kremlin-watchers say he, not his successor, takes many of the crucial decisions. Putin is now prime minister under Medvedev.

Medvedev said, when proposing the change last week, that it was needed to give the head of state time to push through reforms. A spokesman for Putin said press reports he planned to return to the Kremlin in an early election were groundless.

The Kremlin has said the proposed change would apply to Medvedev’s successors but not to him.

Medvedev also submitted a draft law on extending the term of the State Duma lower house of parliament -- where Putin’s party has a comfortable majority -- from four to five years.

“The President of Russia ... has sent to the State Duma draft laws on amendments to the constitution of the Russian Federation ‘on changes to the term of office of the president of the Russian Federation and the State Duma’,” a Kremlin statement said.

The draft laws are likely to win parliamentary approval without problems. “We are not going to drag out this issue,” Alexander Moskalets, a senior lawmaker with Putin’s United Russia party, told Reuters.

Kremlin critics have said the constitutional changes could be used as a legal pretext to call an early election, enabling Putin to make a comeback.

The constitution bars presidents from serving more than two consecutive terms, but there is no restriction on returning to the job after an interval.

“A scenario where early presidential and Duma elections are announced after these amendments to the constitution are adopted looks the most likely today,” the United Civil Front, led by former world chess champion Garry Kasparov, said in a statement.

“Hardly anyone in Russia can today have any doubts about who in that case will be running for the highest state post,” the opposition grouping said in the statement issued last week.

“In this way, the authorities will solve the problem of a third term for President Putin not being legitimate.”