Dhaka, July 20 -- Japan's shaky ruling coalition is likely to lose control of 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 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 need 50 seats to secure the 248-seat upper chamber in an election where half the seats were up for grabs. They are forecast to hold 32 to 51 seats, the exit poll by public broadcaster NHK showed.

Other broadcasters forecast t...