A voter casts her ballot at a polling station in Seoul, Dec. 19, 2012. Polls opened early Wednesday morning in South Korea's closely contested presidential election, which pits the daughter of a military strongman against a former human rights lawyer once jailed for protesting his rule. (Xinhua/Park Jin-hee)

Tens of millions of South Koreans are voting Wednesday to decide whether to keep conservatives in power or hand the job to liberals.

Voting continues nationwide until 6 p.m. local time and media are expected to project results at that time based on exit polls.

Voter turnout is crucial, with a slew of opinion polls suggesting a neck-and-neck race between conservative Park Geun-hye of the ruling Saenuri party and her liberal rival Moon Jae-in of the main opposition Democratic United Party.

Park garners solid support from older voters who tend to turn out in force, while Moon is more popular with younger voters whose support does not always translate into a ballot.

Moon's campaign has pushed hard for an increased turnout among young voters, and analysts said a turnout of more than 70 percent may guarantee a win for Moon.

Voter turnout was 26.4 percent as of 11 a.m. local time, up 4.6 percent from the previous 2007 poll, the country's election watchdog said.

Voters have expressed the disappointment with the outgoing administration of President Lee Myung-bak for its failure to deliver on promises to improve the economy, and appear determined to elect a new leader who can pull the economy out of the mire.

"I want a president who can make the lives of ordinary people better because our country is in a very difficult situation now," said Bae young-ae, a 66-year-old grocery store owner who was waiting in a queue for her turn to enter a polling station in central Seoul Wednesday morning.

"Customers complain of high food prices, but it's the government's fault, not mine. A new president should be someone who can take care of ordinary people," Bae said.

Park and Moon both have promised to realize economic democratization, increase welfare spending and boost support for small and medium-sized companies.

While they agree in their diagnosis of social and economic ills, the two mainly differ on how far the measures they propose should go.

The two candidates pledged to correct an economy led by chaebol, the country's family-owned giant conglomerates, although Park is believed to have a softer stance toward them.

"I voted for a candidate who truly prioritizes policies for ordinary people and who can revamp the chaebol economy," said a 60-year-old voter who did not want to give his name. "A candidate who can save the economy for ordinary people should be the president."