MOSCOW — President Vladimir V. Putin of Russia submitted constitutional amendments on Monday that empower a previously toothless advisory council as a powerful policy arbiter, setting up what could be a future role for himself as Russia’s long-term paramount leader.

Short on vital details, the proposed changes shed little light on Mr. Putin’s exact plans and set off another round of speculation about the future of Russia’s longest-serving leader since Stalin.

The amendments sharply increase the role of the State Council, turning what is currently a largely decorative body into a new locus of power that will “determine the main direction of domestic and foreign policy.” Not specified, however, is how the council’s head will be chosen and whether the body will be subordinate to the presidency.

The council is currently chaired by Mr. Putin in his role as president, a position he first took when President Boris N. Yeltsin resigned on New Year’s Eve 1999. But Mr. Putin is barred from seeking re-election once his current term runs out in 2024. His constitutional changes, first announced in a state of the nation address last Wednesday, are widely viewed as an effort to prolong his hold on power after the end of his presidential term.