With polls suggesting the Liberal Democratic Party-New Komeito pair will probably return to power after Sunday's Lower House election, political analysts and insiders are already focusing on whether the alliance can win a majority in the Upper House race next summer and control the Diet.
On Friday, two Upper House members left the chamber's parliamentary group led by the LDP, dropping the group's strength to 83 in the 242-seat chamber, which currently has six vacancies.
As a result, the LDP-New Komeito alliance now holds 102 seats, 16 short of a majority.