Polls have opened in Ukraine’s presidential runoff, as the nation’s incumbent leader struggles to fend off a strong challenge by a comedian.

Opinion surveys ahead of the vote have shown 53-year-old President Petro Poroshenko trailing far behind comic actor Volodymyr Zelenskiy, reflecting public dismay with endemic corruption, a moribund economy and a five-year fight against Russia-backed insurgents in the country’s east.

Mr Zelenskiy, 41, got twice as many votes as Mr Poroshenko in the first round three weeks ago.

Ukrainian president Petro Poroshenko and challenger Volodymyr Zelenskiy
Ukrainian president Petro Poroshenko and challenger Volodymyr Zelenskiy (Vadim Ghirda/AP)

Like his TV sitcom character, a teacher thrust into the presidency after a video of him blasting corruption goes viral, he has focused on fighting corruption, riding the wave of public distrust of Ukraine’s political elite.

“I have grown up under the old politicians and only have seen empty promises, lies and corruption,” said Lyudmila Potrebko, a 22-year-old computer programmer who cast her ballot for Mr Zelenskiy. “It’s time to change that.”

Mr Poroshenko, a billionaire confectionery magnate before taking office, has relied on traditional political barnstorming, using sympathetic television stations to extensively cover his appearances.

An Orthodox priest casts his ballot in Kiev
An Orthodox priest casts his ballot in Kiev (Sergei Grits/AP)

Mr Zelenskiy, however, has largely stayed away from the campaign trail and eschewed interviews. He has run his campaign mainly on Instagram, where he has 3.7 million followers.

Mr Poroshenko’s attempts to counter the challenger online have often been awkward, including a video that showed Mr Zelenskiy being run over by a truck with a streak resembling a line of cocaine left behind. There is no evidence that Mr Zelenskiy, a fitness fan, uses drugs.

The campaign was marked by fierce mutual criticism and a jockeying for dominance, culminating in Friday’s debate at the nation’s largest sports arena in which both rivals fell on their knees in a melodramatic moment to ask forgiveness of those who lost relatives on the eastern battlefront.