TOKYO -- The Japanese public voted on Sunday to determine the makeup of the nation's upper house, in a crucial vote for Prime Minister Shigeru Ishiba, whose coalition is fighting to hold on to its majority -- one that it lost in the lower chamber last autumn.

Japanese were voting Sunday for seats in the smaller of Japan's two parliamentary houses in a key election with Prime Minister Shigeru Ishiba and his ruling coalition facing a possible defeat that could worsen the country's political instability.

Japan’s ruling bloc is girding itself for a backlash as voters cast their ballots in an election that opposition parties have made a referendum on inflation, immigration and the leadership of Prime Minister Shigeru Ishiba.