[18][19][20][21] Prior to the election on 28 September 2017, the DP House of Representatives caucus dissolved in order for party members to stand as candidates for Tokyo governor Yuriko Koike's Party of Hope or as independents in the upcoming election.

The Japanese Communist Party (JCP), in turn, pulled their own candidate from running in Edano's district so as to not take away votes from him.

[27] On 19 August 2020, the CDP announced that it would merge with the majority of the Democratic Party For the People (DPP) as well as some independent Diet members in September of that year.

[31] SDP leader Mizuho Fukushima was opposed to the merger agreement and as a result remained in the Social Democratic Party.

[31] The CDP contested the 2021 general election in an electoral pact co-operating with the JCP, Reiwa Shinsengumi and continuing DPP and SDP parties in fielding single opposition candidates in single-seat constituencies.

[32] Edano resigned as party leader following the election on 2 November 2021, due to poorer than expected electoral results, in which the CDP fell from 110 to 96 seats.

Formerly a member of the DPP, he said that the two parties are regarded by the public as "close" and "thought to be like brothers" and "expressed support for a tie-up" between the two.

[40] In the 2024 general election held on 27 October 2024, the CDP greatly increased their seat count in the House of Representatives to 148, depriving the ruling Liberal Democratic Party of their majority.

[67] The 2021 election platform offered support for progressive taxation, a pledge for additional welfare payments for citizens on low incomes, and raising the capital gains tax rate to 25% by 2023.

[68] The CDP's 2024 platform supported raising the minimum wage, the abolition of tuition fees, free school meals, gender equality legislation and reform of laws regulating use of surnames following marriage in Japan.

[71] The following policies are set forth under the title "Enrich your life with a change of government: Seven promises of the Constitutional Democratic Party."