TOKYO (AP) — 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. With just one more seat to be decided, the coalition had 47 seats.

The loss is another blow to Ishiba’s coalition, making it a minority in both houses following its October defeat in the lower house election, and worsening Japan’s political instability. It was the first time the LDP has lost a majority in both houses of parliament since the party’s foundation in 1955.

Despite the loss, Ishiba expressed determination to stay on and not create a political vacuum to tackle challenges such as U.S. tariff threats, but he could face calls from within his party to step down or find another coalition partner.