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.

Japanese voters are casting ballots in a key parliamentary election. Prime Minister Shigeru Ishiba’s ruling coalition faces potential losses that could deepen political instability.

Shigeru Ishiba of the long-governing Liberal Democratic Party could face calls to resign if his party fares poorly in Sunday’s Upper House elections.