The official campaign for South Korea's presidential elections in December has begun, with two leading candidates vying for the top job. The country's economy and relations with North Korea are among the top issues dominating the campaign.

In the last two weeks, the presidential election campaign has been transformed, after two left-wing candidates joined forces to create a broad liberal coalition.

This is now headed by Roh Moo-hyun, of the pro-government Millennium Democratic Party. After forming the alliance, Mr. Roh's popularity soared, and according to some final pre-election opinion polls, Mr. Roh has overtaken the conservative candidate, Lee Hoi-chang, of the Grand National Party.

Until now, Mr. Lee has consistently led in the polls. Mr. Roh is a former human rights lawyer, who made his name in the 1980s by opposing the military dictatorship. In the past, he has defended student and labor activists, and his base of support is among South Koreans in their 30s, who are tired of the corrupt political scene.

Mr. Lee also has a background in the law, and has been a supreme court judge and prime minister. This is his second try for the top office, after losing to President Kim Dae-jung in 1997.

Mr. Lee says he is trying to harness support among those who feel disappointed by the present administration. He is calling on South Koreans to harness their knowledge and experience to propel the country into the future.

The differences between the two leading candidates are striking over policy toward communist North Korea. Roh Moo-hyun has been a consistent supporter of President Kim Dae-jung's so-called "Sunshine Policy" toward Pyongyang. He has maintained this line, despite recent U.S. revelations that North Korea is developing a nuclear program.

Mr. Roh wants Washington and Pyongyang to enter into negotiations to resolve the issue. The United States has said North Korea must first dismantle its program unconditionally.

Conservative Mr. Lee is more sympathetic to Washington's position. He has been sharply critical of the government's North Korean policy, claiming Seoul has given away too much, and gotten little in return.

But he surprised many South Koreans by saying Wednesday, that he would be prepared to hold a summit with the North Korean leader, if he won the election.

On economic issues, both candidates support reforms introduced by the present administration, which followed the country's bailout by the International Monetary Fund in 1998. But there, the similarity ends.

The liberal Mr. Roh is seen as being pro-labor, and has pledged to maintain the curbs imposed on large industrial conglomerates, following the IMF bailout.

During the opening day of the campaign Wednesday, Mr. Roh pledged to strengthen the country's economy. He says he would end the factional infighting between politicians, which prevented them from committing themselves to the economy.

In contrast, Lee Hoi-chang is more pro-business, and supports a market-oriented approach to economic policy.

Five candidates in total have registered for the election, planned for December 19. Under its constitution, South Korean President Kim Dae-jung is not allowed to run for a second five-year term. His presidency ends in February.