Voters headed to the polls Sunday for an Upper House election that could considerably alter the Japanese political landscape.

Opinion polls have indicated the ruling Liberal Democratic Party-Komeito coalition could lose its long-held majority in the upper chamber, a development that would likely exacerbate instability amid significant challenges at home and abroad.

Since the Lower House election, which saw the coalition fall short of a majority, the LDP hasn’t been able to rehabilitate its standing in the eyes of many voters. Sunday’s vote will offer a snapshot of the current mood around Prime Minister Shigeru Ishiba, who also serves as LDP leader and whose political standing has long been tarnished by low approval ratings.