Russia’s government resigned in a shock announcement on Wednesday after President Vladimir Putin proposed a shake-up of the constitution.

The announcement by Putin’s longtime ally Dmitry Medvedev came after the president used his annual state of the nation address to call for a nationwide vote on a package of constitutional reforms.

The resignation raises deep questions about the long-term shape of Russia’s political system and the future of Putin, who is due to step down at the end of his fourth Kremlin term in 2024.