Japan’s ruling coalition is likely to lose its majority in the upper house, exit polls showed after Sunday’s election, potentially heralding political turmoil as a tariff deadline with the United States looms.

While the ballot does not directly determine whether Prime Minister Shigeru Ishiba’s shaky minority government falls, it heaps pressure on the embattled leader who also lost control of the more powerful lower house in October.

Ishiba’s Liberal Democratic Party (LDP) and coalition partner Komeito needed 50 seats to retain control of the 248-seat upper chamber in an election where half the seats were up for grabs. They are forecast to secure 32 to 51 seats, the exit poll by public broadcaster NHK showed.

Other broadcasters forecast the ruling coalition would hold 41-43 seats. If the coalition holds less than 46 seats, it would mark its worst result since the coalition was formed in 1999.

That comes on top of its worst showing in 15 years in October’s lower house election, a vote which has left Ishiba’s administration vulnerable to no-confidence motions and calls from within his own party for leadership change.