SEOUL // South Korea's main opposition Democratic United Party admitted defeat in yesterday's legislative election in a tight race, Kyodo News reported.
The party, which was once forecast to win the election, apologised to supporters for the disappointing result.
The election was seen as a key test ahead of December's presidential vote.
Counting was continuing late last night.
But with almost 90 per cent of ballots counted, state broadcaster KBS forecast 152 seats for the ruling New Frontier Party (NFP) in the 300-member National Assembly.
It predicted 128 for the centre-left Democratic United Party (DUP), which had been tipped to score an easy victory in opinion polls.
"The DUP apologises for disappointing [supporters]," party secretary-general Park Sun-Sook told reporters.
It is the first time for two decades that the presidential and parliamentary elections fall in the same year.
The ruling party had struggled to preserve its parliamentary majority to pave the way for a second successive presidential victory in eight months' time.
It had 165 seats in the outgoing parliament against 89 for the DUP.
Rival parties are still neck-and-neck in some 20 districts but the outcome is expected to bolster the position of NFP leader Park Geun-hye, a presidential hopeful.
President Lee Myung-bak cannot constitutionally stand for a second term.
With economic concerns sidelining worries over North Korea, the DUP tried to exploit discontent over rising prices, high education and housing costs, job difficulties, a widening income gap and a weak welfare system.
The ruling party depicted its opponents as socially divisive and bent on undermining a decades-old security alliance with the United States, particularly through their vow to renegotiate a recently ratified free trade deal with the US.
The DUP meanwhile called on voters to pass judgement on President Lee Myung-Bak's administration.
North Korea's impending rocket launch is the focus of international attention but has barely figured in the election campaign in the South, which is used to tension with its communist neighbour.
Pyongyang, nevertheless, has repeatedly urged South Koreans to vote out the conservatives who scrapped a cross-border aid and engagement policy.