SEOUL — South Korean presidential front-runner Lee Jae-myung said on Sunday the deadline to reach a deal with the US on trade tariffs needs to be reconsidered to find a mutually beneficial agreement between the two countries.

Tariff negotiations with the United States will be one of the biggest challenges for the winner of the June 3 election, Lee told a news conference.

The snap election was called after Yoon Suk-yeol was impeached as president and removed from office for briefly declaring martial law in December. Lee, from the main opposition Democratic Party of Korea, is leading in opinion polls over presidential contestants.

Seoul and Washington have said they aim to craft a package on tariffs and economic cooperation by July 8. But the South Korean minister of trade and industry said recently there was not enough time and delays would be possible due to the election.

"There is not much time," Lee said. "Isn't diplomacy something that benefits both sides? If one country benefits and the other country suffers unilaterally, that is not diplomacy. It is called plunder."

He called for mutual respect between the two countries, saying they "need to reconsider whether the timeline set by one side should be bound to".

Lee said South Korea must compile an extra budget to boost the economy in the short term and vowed that if elected he would form and head a task force to tackle the slowing economy.

"I will swiftly prepare immediately actionable economic measures and actively respond to the domestic economic slowdown with the determination to fight the recession," he said.

"We should maintain and strengthen our powerful defense capabilities, military power and strengthen the South Korea-US security alliance, but find a path toward dialogue, cooperation, communication and coexistence where possible," said Lee, who considers pragmatism as a key to diplomacy.

Lee is leading the race with 45 percent support ahead of conservative rival Kim Moon-soo, Yoon's labor minister, with 36 percent support in a Gallup Korea poll released on Friday.

Kim has been closing the initially double-digit gap with Lee. Asked about his recent decline in polls, Lee said he was confident that South Koreans would not choose those who supported or staged the "insurrection", referring to the criminal charges against Yoon over martial law.

Agencies Via Xinhua