The ruling Liberal Democratic Party (LDP), its coalition partner Komeito and the opposition Initiatives from Osaka (IFO) party secured a combined 77 seats in the July 10 House of Councillors election, more than two-thirds of upper house seats necessary to propose constitutional amendment.
The LDP captured 56 seats, Komeito won 14 and the IFO garnered seven. Including 88 uncontested seats that the three parties and others in favor of constitutional revisions hold, those in the pro-amendment camp have secured 165 seats, surpassing two-thirds or 162.
The ruling coalition won over two-thirds of seats in the House of Representatives in the December 2014 general election. Under Article 96 of the Constitution, constitutional amendment must be initiated by the Diet through a concurring vote of two-thirds of all members of each chamber and approved by a simple majority in a referendum.
The LDP won 19 seats in the proportional representation bloc, one seat more than in the previous 2013 upper house poll. The LDP additionally endorsed Kenji Nakanishi, an independent who successfully ran in the Kanagawa prefectural constituency, bringing the total number of seats the party won in the July 10 race in constituencies and the proportional representation bloc to 56, one seat short of securing a single-party majority.
Komeito won 14 seats, five more than the nine contested seats held by the party prior to the July 10 poll.
The largest opposition Democratic Party secured 11 seats through the proportional representation system, more than seven its predecessor Democratic Party of Japan (DPJ) had garnered in the previous 2013 poll. In total, the party won 32 seats, almost twice the number the DPJ had secured in the previous race, but fell short of 46 up for grabs this time.
The IFO, two of whose seats were contested in the July 10 election, secured seven, while the Japanese Communist Party captured six seats, just twice the number of its contested seats. The Social Democratic Party and the People's Life Party won one seat each in the proportional representation bloc.