Croatia’s president, Kolinda Grabar-Kitarović, will seek re-election on Sunday as the country gears up to assume the rotating presidency of the EU for the first time.

She was initially expected to have an easy ride, but her campaign has been complicated by the rise of a populist, anti-establishment folk musician, Miroslav Škoro, which has led her to move to the right to compete for votes.

“We have pulled Croatia out of apathy and gloom. Croatia is no longer on its knees, it’s upright. Croatia is again known in the world for its successes,” Grabar-Kitarović told a campaign rally in Zagreb on Thursday evening.

A member of the ruling Croatian Democratic Union (HDZ), Grabar-Kitarović became the country’s first female president in 2015. She was previously foreign minister and assistant secretary general of Nato.

She came to further prominence during Croatia’s run to the men’s football World Cup final last year, when she travelled to Russia to cheer on the team and appeared to strike up a warm relationship with Vladimir Putin, whom she presented with a Croatian football shirt.

A cyclist rides past a poster of the populist presidential candidate Miroslav Škoro. Photograph: Darko Bandić/AP

While positioned as a centre-right politician, she has been accused of engaging in “dog-whistle politics” to co-opt far-right supporters, an accusation that has intensified during this campaign.

Grabar-Kitarović, Škoro and the former Social Democrat prime minister Zoran Milanović are the frontrunners in a field of 11. Polls show any two of the three could make it into a likely second-round runoff due in early January.

“She has been going to the hard right, partly to face off the challenge of Škoro,” said Florian Bieber, a political scientist at the University of Graz. “It really pushed the whole debate to the hard right and nationalist themes. It’s not a very positive campaign.”

Grabar-Kitarović has appeared uneasy on the campaign trail. She was widely mocked for a number of strange statements, including a promise of jobs that would pay €8,000 (£6,800) a month, almost 10 times the current average wage. At one point her campaign bus was involved in an accident and left without stopping.

“Although still the favourite to win, she is behaving defensively and has made a series of pretty incredible blunders,” said Tena Prelec, a researcher at Oxford University’s department of politics and international relations.

Škoro, who was once a HDZ member, has set himself up as an outsider standing againsthis former party and the Social Democrats, the two dominant political forces in Croatia since the country’s independence.

Among his controversial campaign statements was a vow to pardon the convicted war criminal Tomislav Merčep, an indication of how the country’s recent past continues to influence contemporary debates.

Prelec said the focus on these issues had come at the expense of those that really mattered to most Croatians, such as corruption, emigration and the politicisation of key institutions.

The country’s HDZ prime minister, Andrej Plenković, has backed Grabar-Kitarović. While the presidency is a largely ceremonial role, the campaign has set the tone of political discourse in the country. “It’s less about power and more about how it skews the public debate,” said Bieber.