Opposition party lawmakers staged a sit-in overnight at the National Assembly’s main chamber after the ruling Grand National Party (GNP) unilaterally approved a bill on ratifying the South Korea-U.S. free trade agreement (FTA).

Lawmakers of the main opposition Democratic Party and minor Democratic Labor Party said the FTA ratification bill is invalid both legally and politically. The legislators then vowed to file a suit to nullify the bill among other efforts to fully protest the passage of the bill.

Opposition lawmakers also urged National Assembly Speaker Park Hee-tae and Vice Speaker Chung Ui-hwa to resign and vowed not to take part in any parliamentary procedures.

As a result, efforts to handle next year’s budget plan by the deadline next Friday have become unclear.

With the passage of the FTA ratification bill, the political circle’s focus may shift to political realignment in preparation for next year’s general and presidential elections.