Now in its ninth month, the war in Iran has hit American pockets hard, and it could shift the balance in key midterm races that decide who controls Congress.

The serious damage to refineries and other facilities in the Middle East, combined with ongoing uncertainty about whether the Strait of Hormuz will remain open, have kept oil prices inflated. Americans have paid for it: The Center for American Progress estimates that the war has cost each US household at least $1,200.

Rising costs are among the reasons the war has been deeply unpopular, and Tuesday’s midterms are likely to be a referendum on how the White House has handled the impact. Democrats are trying to use that to their advantage to win races in places where the high price of diesel, home heating oil, and fertilizer are particularly top-of-mind for voters. Here’s how it’s playing out in key states across the country.

A Fight Over Diesel in Texas High diesel prices are affecting voters in every state, but it’s a particularly acute problem in Texas, where Governor Greg Abbott issued a state of emergency over diesel prices last month. The state, which traditionally had some of the lowest diesel prices in the country, has seen prices surge more than 80 percent compared to last year. That’s roughly 10 percent above the national average, according to AAA data.

Abbott is facing a tough reelection campaign, and his opponent, Gina Hinojosa, has used the war as an attack line against Abbott. She has pressured Abbott to suspend a state gas tax on diesel. The Texas Democratic Party issued a statement following the state of the emergency declaration calling on Abbott to “demand that Donald Trump lift his absurd tariffs and halt the unnecessary war that are driving up costs for Texans.”

Fuel prices have also factored into the heated Senate race between Democrat James Talarico and Texas attorney general Ken Paxton. Talarico has also called on Paxton to support suspending the federal gas tax—a move that is supported by some high-ranking Republicans, including Trump—and accused him of “choosing to support the war driving up diesel prices.”High Heating Costs in Maine More than 80 percent of the 4.9 million households in the US that heat their homes with oil are located in the Northeast. It’s a particularly popular form of heating in Maine, where more than half of households in the state rely on it.

With winter approaching and prices now nearly double what they were last year, heating oil has played a big role in the contentious Senate race between incumbent Republican Susan Collins and Democratic challenger Troy Jackson.

State Democrats have seized on Collins’ early support of the war to attack her. (She has come out against the conflict in recent months.) In a sign that the race is uncomfortably close, the White House released a tranche of heating oil reserves in a bid to temporarily draw down the price of the fuel.

“Families are spending a lot more to fill up a tank than they did a year ago,” says Mark Wolfe, the executive director of the National Energy Assistance Directors Association, which predicted that households in the Northeast could spend an additional $3.8 billion on heating oil this winter.

Unlike price spikes on diesel fuel, which may filter to consumers through higher prices on a number of different products, heating oil itself is a consumer good: Families pay directly for the oil to be delivered to their homes. The impact to voters’ pocketbooks, Wolfe says, is “very immediate.”

Fertilizer Prices Shake the Midwest High diesel prices have hurt farmers, but so, too, has the cost of fertilizer.

Nitrogen-based fertilizers, like ammonia and urea, are made from natural gas by-products, and some of the world’s biggest producers are based in the Middle East. While some production has restarted, it remains well below its prewar average. Urea prices spiked earlier this year.

“If you're going to plant crops like wheat and corn, you have to apply nitrogen,” says Josh Linville, the vice president of fertilizer at financial services company StoneX.

Sulfur, which is also made from oil and gas by-products, is a crucial ingredient in other types of fertilizer. Sulfur prices have more than doubled since the start of this year, thanks to supply chain issues in the Gulf. Farmers who use sulfur-based fertilizers, Linville says, have had to make tough choices about how to manage their crops.

These stresses have put fertilizer front and center in tight races in states like Ohio, Iowa, and Illinois. VoteVets, a PAC that supports Democrats, aired an attack ad against Republican Senate nominee Ashley Hinson in Iowa earlier this month that highlights her record of voting in favor of attacks on Iran.

“Record gas prices. Record fertilizer costs. Farms going under,” the ad intones. “And Ashley Henson’s voting for all of it in Washington.”In Ohio, Democrat Sherrod Brown’s campaign has aired an ad in recent weeks pinning high diesel and fertilizer costs on his opponent, incumbent senator John Husted, again by bringing up his track record of voting for the war.

Whether that can peel off enough farm voters—a core Republican constituency—to swing the race to Brown remains to be seen. But the costs on farmers are mounting, and there’s little relief in sight with uncertainty looming over Iran. “That farmer’s sitting there saying, ‘I have to farm, but it’s not a matter of can I make money,’” Linville says. “It’s ‘how do I lose the least amount of money next year?’”