Serbia’s president, Aleksandar Vucic, resigned on Sunday to pursue the prime minister’s post in an upcoming early parliamentary election, according to the AP.

The election, the outlet said, will test his firm rule in the Balkan country after nearly two years of protests. The snap election is set for October 25, and a student-led movement is mounting the most serious challenge to his rule in more than a decade, according to Al Jazeera.