The nation's top political parties have submitted a bill to amend the electoral law to lower the voting age for national elections to 18 from 20.

Six parties, including the Liberal Democratic Party-Komeito ruling coalition and the Democratic Party of Japan, the main opposition force, submitted the bill Thursday for passage during the current Diet session, which runs through June 24.

If the bill passes, 18- and 19-year-olds will get their first chance to vote in next year's Upper House election, unless the Lower House is dissolved before then. Some 2.4 million people aged 18 and 19 are expected to become voters next year if the proposal becomes law.