South Korea's ruling party claimed a majority Thursday in a parliamentary vote that centered on domestic issues but had implications for Seoul's relationship with the North.

President Lee Myung-bak's conservative Saenuri Party was expected to win at least 152 seats while his liberal rivals were set to claim 140 in the race for 300 parliamentary seats, the National Election Commission said with 1 percent of ballots left uncounted. South Koreans went to the polls a day earlier.

Ties between the two Koreas plummeted during Lee's tenure, with two attacks Seoul blames on Pyongyang killing 50 South Koreans in 2010. North Korea also conducted a long-range rocket launch and tested a nuclear device in 2009.

After North Korean leader Kim Jong Il died in December and his son Kim Jong Un took over, Pyongyang stepped up criticism of Lee, accusing his government of failing to pay proper respect to Kim Jong Il.

South Korea, the U.S. and others have urged the North to cancel a rocket launch it plans as soon as Thursday, calling it a cover to test long-range missile technology rather than the peaceful satellite launch Pyongyang claims. Lee's government has said it will shoot down any rocket parts that threaten to fall onto the South's territory.

Despite Pyongyang's rocket preparations, the launch wasn't a major issue in Wednesday's elections, which were largely seen as a way to gauge public sentiment ahead of December's presidential polls. Voters have said they care more about economic and other domestic issues.

Chung Jin-young, a political scientist at South Korea's Kyung Hee University, said Wednesday that a liberal win would be favorable for North Korea because that could put pressure on Lee to adopt an appeasement policy on Pyongyang.

Kim Doh-jong, a professor at Seoul's Myongji University, said a big liberal win still would not change Lee's stance on North Korea.

Lee's single five-year term ends early next year.

Key potential contenders vying to succeed Lee are Park Geun-hye, a top ruling party official and the eldest daughter of late President Park Chung-hee; Moon Jae-in, a liberal opposition leader who served as former President Roh Moo-hyun's chief of staff; and Ahn Cheol-soo, a university professor and founder of one of South Korea's most successful software companies.