Voting in South Korea’s presidential election appeared too close to call on Wednesday, according to early results and exit polls, after a hard-fought campaign that pitted an outspoken liberal ex-governor against a conservative former top prosecutor.

The election boiled down to a two-way showdown between Lee Jae-myung, the former governor of South Korea’s most populous Gyeonggi province, and his main conservative challenger, Yoon Suk Yeol. The two spent months slamming, mocking and demonising each other in one of the most bitter political campaigns in recent memory, aggravating the country’s already severe domestic divisions.

With about 30% of the ballots counted, Mr Lee had 49.6% of the votes against Mr Yoon’s 47.1%.

A joint exit poll by the KBS, MBC and SBS television stations earlier predicted that Mr Yoon, from the opposition People Power Party, would win 48.4% of votes cast, beating Mr Lee of the Democratic Party with 47.8%.

But another exit poll by the JTBC television network projected that Mr Lee would defeat Mr Yoon by 0.7 percentage points.

Election officials said vote counting may take longer than usual because of an extended voting time for Covid-19 patients, and that the winner may not be clear until early on Thursday.

About 44 million South Koreans aged 18 or order were eligible to vote out of the country’s 52 million people. About 16 million cast ballots during early voting last week. The tentative turnout was 77.1% after polls closed on Wednesday, the fifth highest since the country restored direct presidential elections in 1987 following decades of military dictatorship, according to the National Election Commission.

The winner of Wednesday’s vote will take office in May and serve a single five-year term as leader of the world’s 10th largest economy.

Mr Lee and Mr Yoon recently agreed that if they won they would not launch politically motivated investigations against the other, but many believe the losing candidate could still face criminal probes over scandals they have been linked to.

Critics say neither candidate has presented a clear strategy for how they would ease the threat from North Korea and its nuclear weapons. They also say voters are skeptical about how both would handle international relations amid the US-China rivalry and how they would address widening economic inequality and runaway housing prices.

“Despite the significance of this year’s election, the race has centred too much on negative campaigning,” said Jang Seung-Jin, a professor at Seoul’s Kookmin University, adding that neither leading candidate laid out a convincing blueprint on how they would lead South Korea.

The election comes as South Korea has been grappling with an Omicron-driven Covid-19 surge. On Wednesday, health authorities reported 342,446 new virus cases, a record high. People infected with the coronavirus voted after regular voting ended on Wednesday evening.

Ahead of the vote, Jeong Eun-yeong, a 48-year-old Seoul resident, said she was agonising over which candidate is “the lesser of two evils”.

“Nobody around me seems happy about voting” for either Mr Lee or Mr Yoon, she said. “We need a leader who would be really devoted to improving the lives of working-class citizens.”

While Mr Lee and Mr Yoon have some similar economic and welfare policies, they’ve clashed over North Korea and other foreign policy issues.

Mr Lee, who has often expressed nationalistic views, calls for exemptions to UN sanctions on North Korea so that dormant inter-Korean economic projects can be revived, and hopes to mediate between the North and the US over the North Korean nuclear crisis. Mr Yoon says he would sternly deal with North Korean provocations and seek to boost trilateral security cooperation with Washington and Tokyo.

On confrontation between Washington, Seoul’s top military ally, and Beijing, its biggest trading partner, Mr Lee says picking a side would pose a greater security threat to South Korea. Mr Yoon wants to enhance the alliance with the US.

After North Korea’s latest reported ballistic missile launch on Saturday, Mr Yoon accused North Korean leader Kim Jong Un of trying to influence the results of the South Korean election in favour of Lee.

“I would (teach) him some manners and make him come to his senses completely,” Mr Yoon told a rally near Seoul.

Mr Lee wrote on Facebook that he would push for a diplomatic solution to North Korean nuclear tensions but will not tolerate any act that would raise animosity.

South Korea’s Constitution limits a president to a single five-year term, so Mr Lee’s party colleague, President Moon Jae-in, could not seek reelection. Mr Moon came to power in 2017 after conservative president Park Geun-hye was impeached and ousted from office over a huge corruption scandal.

With conservatives initially in shambles after Ms Park’s fall, Mr Moon’s approval rating at one point hit 83% as he pushed hard to achieve reconciliation with North Korea and delve into alleged corruption by past conservative leaders. He eventually faced a strong backlash as talks on North Korea’s nuclear program faltered and his anti-corruption drive raised questions of fairness.

Mr Yoon had been Mr Moon’s prosecutor general but resigned and joined the opposition last year following infighting over probes of Mr Moon’s allies. Mr Yoon said those investigations were objective and principled, but Mr Moon’s supporters said he was trying to thwart Mr Moon’s prosecution reforms and elevate his own political standing.

Mr Yoon’s critics have also attacked him over a lack of experience in party politics, foreign policy and other key state affairs. Mr Yoon has responded that he would let experienced officials handle state affairs that require expertise.

Mr Lee, a former human rights lawyer who entered local politics in 2005, has established an image as a tough-speaking anti-elitist who can get things done and fix establishment politics. But his opponents call him a dangerous populist relying on divisions and demonising opponents.

Mr Yoon has launched a political offensive against Mr Lee over allegations that he was a key figure in a corrupt land development project in the city of Seongnam when he was mayor there. Mr Lee has tried to link Mr Yoon to the same scandal. Both of their wives have offered public apologies over separate scandals.