In this Dec. 31, 2019, photo, a boy takes photo with the incumbent president Kolinda Grabar Kitarovic at a rally in Marija Bistrica near Zagreb, Croatia. Croatia's bitterly contested presidential race is headed for a finale this weekend to decide whether a conservative or a liberal will lead the country during its first ever chairmanship over the European Union. (AP Photo/Aleksandar Kavic)

ZAGREB, Croatia - Voters in Croatia were casting ballots Sunday to choose a new president in a fiercely contested runoff, with a liberal opposition candidate challenging the conservative incumbent while the country presides over the European Union for the first time.

Croatia took over the EU's rotating presidency on Jan. 1. for the first time since joining the bloc in 2013. This means that the EU's newest member state will be tasked for six months with overseeing Britain's divorce from the EU on Jan. 31 and the start of post-Brexit talks.

Sunday's presidential runoff is expected to be a very tight, unpredictable vote.

President Kolinda Grabar Kitarovic is running for a second term, challenged by leftist former Prime Minister Zoran Milanovic, the top two contenders after the first round of voting on Dec. 22.

Milanovic won slightly more votes than Grabar Kitarovic in the first round but analysts say there's no clear favourite in the runoff. There are 3.8 million voters in Croatia, a country of 4.2 million that is also a member of NATO.

The two candidates represent the two main political options in Croatia. Grabar Kitarovic is backed by the governing, conservative Croatian Democratic Union, a dominating political force since the country split from the former Yugoslavia in 1991, while Milanovic enjoys support from the leftist Social Democrats and their liberal allies.

Even though Croatia's presidency is largely ceremonial, Sunday's election is an important test ahead of a parliamentary election expected later this year. Milanovic's victory over Grabar Kitarovic would rattle the conservative government during the crucial EU presidency and weaken its grip on power in an election year.

Upon voting in the capital of Zagreb, Milanovic said the presidential election was a first step toward changes.

“This is important, everyone should come out to vote, virtually everyone," Milanovic said. “The election is not a clash with anyone but an attempt to create a normal Croatia."

Grabar Kitarovic said “today we decide what Croatia will look like in the next several years."

“Each person is important, each vote is important," she said. “Let's build together a Croatia that will look forward and not back."

Support for Grabar Kitarovic has ebbed following a series of gaffes in the election campaign. The 51-year-old had a career in diplomacy and in NATO before becoming Croatia's first female president in 2015. Going into the runoff, Grabar Kitarovic evoked Croatia's unity during the 1991-95 war in a bid to attract far-right votes.

The 53-year-old Milanovic is hoping to regain some clout for liberals in the predominantly conservative nation where the Catholic church holds significant influence.

Prone to populist outbursts while prime minister, Milanovic lost popularity after the ouster of his government in 2016. He now says he has learned from the experience and matured.

Although Croatia is a member of the EU, it still has corruption problems and economic woes, issues not resolved since its devastating 1991-95 war to break free of the Serb-led Yugoslav federation.

News from © The Associated Press, 2020