The setbacks suffered by the Social Democratic Party and the Japanese Communist Party, which were both reduced to less than 10 seats in Sunday's House of Representatives election, mark a sharp decline in forces committed to opposing any change to the war-renouncing Constitution.

Their decline contrasts sharply with the big gains posted by the Democratic Party of Japan, the main opposition force, which does not rule out future constitutional amendments.

With the Liberal Democratic Party promising to draft an amendment as early as 2005, the fall of the SDP and JCP could influence Diet debate on the matter.