Democratic Party of Japan leader Naoto Kan said Tuesday that people should be legally obliged to vote in national elections.

The main opposition party was defeated Sunday in all three House of Representatives by-elections, in which voter turnouts were at record lows.

Voter turnout in the Saitama No. 8 constituency was 35.22 percent, down 19.74 percentage points from the Lower House general election in November. The figure stood at 55.52 percent in the Hiroshima No. 5 constituency, down 9.04 points, and 54.92 percent in the Kagoshima No. 5 district, down 10.31 points, according to election administration commissions.