Photo/IllutrationYukio Edano, center, the head of the opposition Constitutional Democratic Party of Japan, shakes hands after an agreement was reached on Sept. 19 to form a unified voting bloc in the Diet among three opposition parties. (Takeshi Iwashita)

To strengthen their voice in Diet deliberations, three opposition voting blocs on Sept. 19 agreed to form a single unified bloc starting from the extraordinary Diet session to be convened in October.

The heads of the Constitutional Democratic Party of Japan (CDP) and the Democratic Party for the People (DPP), as well as the Lower House voting bloc calling itself the Reviewing Group on Social Security Policy, agreed to the establishment of a bloc with 117 seats in the Lower House and 61 in the Upper House.

The figure in the more powerful Lower House will represent the largest opposition voting bloc since 2012 when Prime Minister Shinzo Abe began his second stint as head of the government.

The agreement was reached by CDP head Yukio Edano, DPP head Yuichiro Tamaki and former Prime Minister Yoshihiko Noda, who heads the reviewing group bloc.

After their meeting, Edano told reporters, "(The ruling coalition) has intensified the egregious nature of how it manages the Diet. By enhancing the cooperation and solidarity among lawmakers with experience and knowledge, we will be able to enter into Diet deliberations with a much greater strength than in the past."

By forming a single voting bloc, the three groups will be able to reduce similar questions during Diet deliberations and more strategically pursue various problems arising from the Abe administration rather than repeat the same questions during plenary and committee sessions. The voting bloc will also have a stronger hand in negotiating with the ruling coalition over the holding of Diet committee sessions.

Along with the formation of the bloc, three independents on Sept. 19 also formally submitted requests to become CDP members.

The ruling coalition brushed aside the latest development, with Hiroshi Moriyama, the Liberal Democratic Party's Diet Affairs Committee chairman, saying, "Nothing will change in Diet management."

All three blocs were once part of the Democratic Party of Japan when it controlled the government, but a split occurred after the party was voted out of power in 2012.

It remains to be seen if the unified voting bloc will lead to the formation of a new party including all members of the new bloc since important policy differences remain.