Japanese Prime Minister Shigeru Ishiba said Monday he will stay in office to tackle challenges such as rising prices and high U.S. tariffs after a weekend election defeat left his coalition with a minority in both parliamentary chambers and triggered calls for his resignation.

This means that Ishiba no longer has easy control over the upper or lower houses of parliament; last October, the LDP lost control of the more powerful lower chamber, marking a major upset for a party that has ruled Japan for most of its post-World War II history.

Japan’s Prime Minister Shigeru Ishiba faces a critical test in Sunday’s upper house election. A loss could deepen political instability as his government struggles with rising prices, U.S.