ZAGREB, Croatia (AP) — Croatia will hold a presidential election on Dec. 29, Prime Minister Andrej Plenković announced on Tuesday.

Authorities are yet to formally set the vote. If no candidate wins an outright majority on Dec. 29, a runoff vote will be held two weeks later.

Incumbent populist President Zoran Milanović has said he would run for reelection. Milanović is backed by opposition Social Democratic Party, while his main challenger is expected to be Dragan Primorac, a candidate of the governing conservatives.

Milanović and Plenković are bitter political rivals. Milanović has opposed the Croatian government's support for Ukraine, including participation of Croatian troops in a NATO-led training mission for Ukrainian soldiers.

The election also will be held as the conservative government was shaken this week by the arrest of the Heath Minister Vili Beroš on suspicion of corruption in procurement deals for Croatian hospitals.

Several other candidates from both the left and right are also expected to join the presidential race.

Milanović, 58, had served as prime minister in the past, before winning the presidential election five years ago by beating then incumbent Kolinda Grabar Kitarović.