In an act of protest, the opposition-controlled House of Councilors on Friday refused to vote on a bill to rectify the unconstitutional vote-value disparity in the House of Representatives and sent it back to the lower chamber.

The ruling Liberal Democratic Party and junior coalition partner New Komeito, which hold a two-thirds majority in the Lower House, pledged to pass the bill again as early as Monday.

Five days before the end of the Diet session, the standoff between the ruling and opposition camps appeared to be devolving into another round of withering "power game" politics.