TOKYO - Japanese Prime Minister Sanae Takaichi said on Monday that she would step down immediately if the ruling bloc fails to secure a majority in the upcoming House of Representatives election.

Speaking at a party leaders' debate held on Monday, Takaichi, who also serves as president of the ruling Liberal Democratic Party (LDP), said that an electoral defeat would leave her unable to continue as prime minister or push ahead with her policy agenda.

When pressed to clarify what she meant by "defeat," Takaichi said she would resign at once if the ruling alliance formed by the LDP and the Japan Innovation Party fails to win more than half of the seats in the lower house.

The debate brought together leaders of several ruling and opposition parties, including Fumitake Fujita, co-representative of Japan Innovation Party, Yoshihiko Noda, co-leader of the opposition Centrist Reform Alliance, and Yuichiro Tamaki, head of the Democratic Party for the People.

The lower house was dissolved on Friday at the outset of its ordinary parliamentary session, with a general election set for Feb 8. The official campaign will start Tuesday, creating a mere 16-day campaign period, the shortest in Japan's postwar history.