MOSCOW – Russian Prime Minister Dmitri A. Medvedev abruptly resigned on Wednesday, shortly after his political boss, President Vladimir V. Putin, swirled the country's political elite with proposals to sweep away constitutional changes that could extend their power to many. years.
Medvedev's office also resigned.
In a statement issued by Russian news agency Tass, Medvedev, a lawyer who has known Putin since they worked together in St. Petersburg in the 1990s, linked the unexpected resignations to a review proposed on Wednesday by Mr. Putin.
As Medvedev's replacement as Prime Minister of Russia, Putin has named Mikhail V. Mishustin, a little-known bureaucrat who has served over the past decade as head of the Federal Tax Service.
Putin, who under current law is expected to resign in 2024, has proposed amending the Russian Constitution to expand the powers of Parliament and a body called the Council of State, which currently has little weight.
Medvedev said such measures would "bring about significant changes" in the "balance of power" between the executive, the legislature and the judiciary. Putin has appointed him deputy head of the Russian Security Council, a powerful body that includes defense and security officials.
It was not immediately clear whether the resignations signaled a crack at the top of Russia's hierarchy or were part of Putin's coordinated but not yet clear plan to retain power and reshape the political system that had been in place with only minor adjustments since the early 90's.
He and Medvedev choreographed movements in the past that allowed Putin to remain in command; In 2008, when Putin faced term limits, Medvedev was elected president. Putin became prime minister, although he remained in royal power in government, and returned to the presidency in 2012 when Medvedev became prime minister.
Putin described the constitutional changes proposed in his annual state of the nation address on Wednesday as an effort to improve democracy. They would be the first major overhaul of Russia's political system since 1993, when Russia's first democratically elected president, Boris N. Yeltsin, sent tanks to central Moscow to subdue a rebel legislature and then ordered a referendum to endorse a new constitution.
Putin, who is abroad but has remained at home for Russia's stagnant economy, has a long history of keeping friends and foes out of balance, and has ensured that he has remained the arbiter of all important decisions in Russia since Yeltsin resigned. on December 31, 1999.
The constitution limits a president to two consecutive terms, which means that without a change, Putin would have to step down in 2024, although he has gave tips on how to keep track of power beyond that date. Russia has been rife with speculation for months about whether it would maneuver to extend its rule – or, if not, who could succeed it.
Already in power for 20 years, more than any Kremlin leader since Stalin, Putin did not illuminate his exact plans on Wednesday, but opened a box of possible Pandora options. The resulting uncertainty unbalances the political elite, helping to ensure that Putin avoids becoming a lame duck and remains the pivot around which the country revolves.
Opposition politicians took advantage of his proposals as evidence that he planned to remain in power indefinitely. Mikhail M. Kasyanov, a former prime minister who is now a fierce critic of Putin, said the president gave a "clear answer" to questions about his future: "I will remain president forever."
Alexander Baunov, political analyst in Moscow, came to a very different conclusion in comments on Twitter: "The president will be weaker and it is beyond doubt now (despite previous speculation that he would somehow remain) that the president will no longer be Putin."
Putin might be considering returning to the prime minister's office, but this time in charge of a newly qualified parliament.
Others saw signs that Putin intended to step down as president and create a system similar to that of Kazakhstan, where longtime President Nursultan A. Nazarbayev, who resigned last year as formal leader of his country, assumed the new title as "leader of the people" and remained in general control.
Medvedev's move from the presidency to the security council reminded many analysts how Putin set him aside as president in 2012.
When Mr. Medvedev took office, he and his boss were not always in sync, much to Mr. Putin's annoyance, who undid several of his measures.
In particular, Putin was angry Medvedev refused to use the 2011 United Nations veto to block air strikes against Libya, attacks that helped topple Colonel Muammar el-Gaddafi's government.