How will Vladimir Putin respond to the growing challenges against him? The Russian president, who turns 65 in October, might presently look unassailable — but maintaining that grip will get harder every year.

Compared to British Prime Minister Theresa May or U.S. President Donald Trump, the Russian president faces scant internal opposition. Recent anti-corruption protests, however, provided him a reminder that no leader can remain in power forever.

Putin will almost certainly win the presidential elections next March. His poll ratings remain high, and Russians have little appetite for the chaos that his fall might bring.