Japan’s voters will deliver a verdict on Prime Minister Shigeru Ishiba’s 10 months in office on Sunday, in an upper house election that takes place amid simmering discontent over inflation and unresolved negotiations with the U.S. on tariffs.

The ruling Liberal Democratic Party and its junior coalition partner Komeito are battling the opposition for 125 spots in the 248-member chamber. Ishiba is aiming to win 50 of those seats to retain an overall majority, a goal that would still mean the coalition losing as many as 16 seats.

Achieving that modest target may help Ishiba shore up his leadership for now, but recent opinion polls indicate the ruling parties are at risk of falling short. That would further destabilize Ishiba’s minority government, potentially adding to jitters among market participants fretting about a further loosening of the nation’s purse strings if his control is diminished.

Ishiba is not in a position to come out of another major loss unscathed, having already suffered a bruising defeat in last October’s election for the more powerful lower house.

While the LDP is still expected to remain the largest party, a poor performance could force Ishiba to resign, an outcome that would derail his policy agenda and complicate ongoing trade talks with the U.S. ahead of an Aug. 1 deadline for raising tariff levels. The last three LDP prime ministers who lost an upper house majority stepped down within two months.

If Ishiba holds on, a weakened mandate would likely force him to seek support from smaller opposition parties to pass legislation. That could mean compromising on key issues, including a temporary sales tax cut aimed at alleviating the cost-of-living crunch. While a reduction would likely please consumers struggling with rising costs, it could unnerve investors worried about the government’s ability to keep control of its debts.

Polling booths open at 7 a.m. and close at 8 p.m., with local media likely to release exit polls soon afterward. Half the seats of the upper house are up for grabs every three years.

The less powerful chamber can’t appoint a prime minister, hold a no-confidence vote or stop the passage of a budget. But it can delay or block other legislation, depending on the level of support, potentially leading to gridlock in the policy-making process.

An NHK poll on Monday showed 24% support for the LDP, followed by 7.8% for the Constitutional Democratic Party, 5.9% for Sanseito and 4.9% for the Democratic Party for the People. The three opposition parties along with the Japan Innovation Party are calling for the sales tax to be lowered, though the parties differ on the extent of the reduction, the duration and how it will be funded.

The populist DPP’s focus on raising people’s disposable income and the right-leaning Sanseito’s “Japanese First” message appear to be resonating with voters, as polls show both parties likely to see a jump in the number of their seats.

Still, inflation ranks as the most pressing issue for voters, with rice, the nation’s staple, around double its price a year ago according to the latest figures released Friday.

Overall consumer prices rose 3.3% in June from the previous year, while a report earlier in the month showed real wages in June declined 2.9%, an indication of how pay increases are lagging prices.

Ishiba is against opposition plans to cut taxes, saying it would endanger Japan’s finances and is instead pledging a one-time cash handout of ¥20,000 ($135). Polls have generally showed that the public would prefer a tax cut over a one-off payment.

The possibility of tax cuts has fueled uneasiness in markets. Yields on Japanese debt recently soared to the highest level in more than two decades. The close market focus on Japan comes amid global jitters over widening fiscal deficits and the need to hold governments accountable for spending beyond their means.

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