In September 2020, the party was re-established following a merger with most of the DPP and SDP caucuses, and some independent lawmakers.

In order to increase the weight of the opposition, the CDP decided to establish joint candidacies with three other progressive parties (JCP, SDP and Reiwa Shinsengumi) in most of the electoral districts for the 2021 general election.

Although the cooperation strategy and a slight increase in votes for the party had led to an increase in the seats obtained compared to 2017 (from 55 to 96), these were still inferior to the number of seats held by the party before the vote (110).

Therefore, Yukio Edano decided to step down, so that a new leadership could reorganize the party in view of the elections for the Upper House in the summer of 2022.

An extraordinary party convention was held at a hotel in Tokyo on the afternoon of November 30.