President Lee Myung-bak's government is in the grip of a political crisis
South Korea's trade minister is visiting Washington to try to secure extra safeguards on beef imports and defuse a political crisis at home.
Kim Jong-hoon will ask US Trade Representative Susan Schwab for a voluntary pledge that beef from cattle over 30 months old will not be shipped.
Street protests have escalated in South Korea over its decision to re-admit US beef imports after a five-year gap.
Protesters are demanding the complete renegotiation of the import deal.
Citing concerns over mad cow disease, or BSE, they have called on supporters to take to the streets again on Friday.
The issue has become a lightning rod for discontent with President Lee Myung-bak.
Protesters are now calling for his resignation - less than four months into his term and despite an offer from the entire South Korean cabinet to resign three days ago.
Mr Kim will try to secure a voluntary agreement from US exporters that they will not send meat from older US cattle, backed by some kind of government guarantee.
But he has refused to bow to demands that the whole import deal be renegotiated, saying that could put a separate free trade agreement (FTA) with the US in jeopardy.
"We have to consider whether it would be a good thing to insist on renegotiation and risk trade retaliation," the minister told a TV talk show Thursday evening, AFP news agency reported.
US deputies have linked the ratification of the FTA with the re-opening of South Korea's market for US beef.
Until imports were suspended in 2003, on the discovery of a case of mad cow disease in the US, Korea was the third largest overseas market for American beef.
Protesters have pledged to take to the streets again on Friday - the sixth anniversary of the deaths of two schoolgirls run down by a US military vehicle, an incident which sparked rallies demanding the withdrawal of US forces from the Korean peninsula.