Japan's ruling coalition lost control of the upper house in an election on Sunday, further weakening Prime Minister Shigeru Ishiba's grip on power even as he vowed to remain party leader, citing a looming tariff deadline with the United States.

The LDP lost its majority in the lower house when Ishiba called a snap general election last October. The LDP has not been in a minority position in both houses simultaneously since its foundation in 1955.

Japanese Prime Minister Shigeru Ishiba’s ruling coalition failed Monday to secure a majority in the 248-seat upper house in a crucial parliamentary election, NHK public television said. Ishiba’s Liberal Democratic Party and its junior coalition partner Komeito needed to win 50 seats on top of the 75 seats they already have to retain their majority.