BUDAPEST, Hungary (AP) — Hungarians were casting ballots Sunday in what is widely seen as Europe’s most consequential election this year, a vote that could unseat populist Prime Minister Viktor Orbán, an ally of President Donald Trump, after 16 years in power.

It’s a key moment for Orbán, the European Union’s longest-serving leader and one of its biggest antagonists, who has traveled a long road from his early days as a liberal, anti-Soviet firebrand to the Russia-friendly nationalist admired today by the global right wing.