Two tiny parties that clashed with the ruling Democratic Party of Japan over policy and then made different decisions on whether to stay in the DPJ-led bloc face a fight for survival in the Upper House election.
The Social Democratic Party took the more dramatic route, severing its ties with the DPJ following their dispute over the Futenma military base in Okinawa, while Kokumin Shinto (People's New Party) stayed in the ruling coalition after its leader left the Cabinet in the brouhaha over how to handle postal reform.
Both parties now appear to be struggling to draw significant voter support.