Voters dealt a blow to the lawmakers who impeached President Roh Moo-hyun (search), swinging behind the liberal Uri Party in a parliamentary election Thursday that could reshape relations with the United States and rival North Korea.

The outcome is expected to strengthen Roh's hand as the Constitutional Court decides the leader's fate. It could also usher in South Korea's first liberal-dominated parliament in four decades.

Opposition parties impeached Roh on March 12 on charges of incompetence and illegal electioneering. Roh's supporters said the charges were politically motivated.

With 72 percent of the vote counted, the Uri Party (search) was forecast to win a majority of 152 seats in the 299-member National Assembly, KBS news reported, citing official tallies.

Uri Party leader Chung Dong-young (search) welcomed earlier exit polls predicting a big win for his party, but urged caution until all votes were counted.

"This election means that the old political forces that have dominated South Korean politics for 44 years are forced to leave the stage, and signals the beginning of new politics," he said.

Prior conservative-dominated parliaments had checked two successive liberal governments' attempts to shape a foreign policy that is more independent of the United States, the country's traditional ally, and to boost exchanges with North Korea despite its nuclear weapons programs and human rights violations.

Trailing the Uri Party was the Grand National Party (search), which was forecast to take 123 seats, followed by the Millennium Democratic Party (search) — formerly the second biggest opposition party — with 9, according to KBS.

Uri had only 49 seats in the outgoing parliament; the GNP had 137, the MDP 61.

The National Election Commission estimated a 59.9 percent voter turnout, up from the previous election's 57.2 percent, reflecting high emotions over Roh's impeachment, the country's first since its founding in 1948.

Roh's presidential powers are suspended while the impeachment Constitutional Court decides on the matter. In the meantime, Prime Minister Goh Kun (search) is running the nation as acting president.

Many believe the strong showing for the Uri Party on Thursday will influence the court to rule in Roh's favor, restoring his powers and political stability.

"The election results give much needed stability to the Roh Moo-hyun government, which has been struggling with its lack of parliamentary support. It gives Roh the means to push for his policies," said Euh Soo-young, a political science professor at Seoul's Ewha Women's University.

Roh wasn't vying for a seat, but the polls were seen as a referendum on his rule. Roh has pledged to resign if the pro-government Uri Party fares poorly. The president is not a Uri member, but has said he plans to join.

In a visit overshadowed by the elections, Vice President Dick Cheney arrived in Seoul just as polls were closing.

Cheney was expected to meet Kun to discuss the North Korean nuclear crisis, the U.S.-South Korean alliance and Seoul's pledge to send 3,600 troops to Iraq.

The United States keeps about 37,000 troops in South Korea.