TOKYO -- Yukio Edano, head of Japan's Constitutional Democratic Party, announced on Tuesday plans to step down following his party's defeat in Sunday's lower house election.

The CDP had mobilized a largely united opposition front, resulting in heated races in many districts but ultimately failing to oust Prime Minister Fumio Kishida's ruling Liberal Democratic Party.

In all, the CDP won only 96 seats on Sunday, less than the 110 it had before the election. The LDP, however, secured a solid majority in the lower house with 261 seats.

Edano joined with other opposition parties like the Japanese Communist Party in a bid to increase their chances of winning, with the opposition camp fielding a single candidate in over 200 single-seat districts.

But following the lackluster outcome, some within the CDP began to question the executive committee's responsibility for the failure. With Edano's resignation, the CDP will be tasked with selecting its new leader as it prepares for the upper house election next summer.