A student-led protest movement has ended the 14-year rule of Serbia's right-wing party, former President Aleksandar Vučić conceded Sunday.

Why it matters: The historic upset sidelines a Balkan strongman who courted President Trump's family and allies, raising questions about future U.S. relations with a country that has balanced ties with Russia and the West.

Vučić's outreach has included the president's son Donald Trump Jr. and longtime ally Richard Grenell, while a proposed development involving Trump's son-in-law Jared Kushner became embroiled in controversy.

The big picture: The movement's electoral breakthrough reflects a broader wave of youth activism in Europe, where young people have mobilized over corruption, education and economic pressures.

The victory could usher in democratic reforms in Serbia, where Vučić consolidated power.

Driving the news: Vučić said Sunday evening it was "clear" that his Serbian Progressive Party had lost to the student-backed electoral movement, although official…