Just when Republicans thought they'd caught a break on gas prices, the collapse of President Trump's Iran deal is derailing their best chance to change the inflation story before the midterms.
Why it matters: Falling gas prices are one of the most tangible ways to ease voter anger over inflation. Renewed combat — and the threat of escalation — has prices shooting back up.
The big picture: Trump has said repeatedly that gas prices will "drop like a rock" when the war is over. But the war doesn't look like it's ending anytime soon.
When the U.S. first launched attacks on Feb. 28, average gas prices nationally were $2.98 a gallon, per AAA. They eclipsed $4.50 in May, gradually dropped to about $3.75 earlier this month, and are now flirting with the $4 mark since combat broke out again.
Zoom in: Surprisingly, Americans typically don't punish politicians for their own economic suffering; instead, they tend to look at how government policies are affecting the country overall.
But gas prices are a different story, says Stanford's Jon Krosnick, who's studied how they affect politics.
"It's hard to think about any other economic indicator where the number is literally posted on signs on the streets where everybody's traveling," he told Axios.
Zoom out: Krosnick, in a 2016 study looking at three decades of evidence, found that a 10-cent increase in gas prices caused a 0.6% drop in a president's approval ratings. He said the effect extends to the president in power's party.
Unlike other instances where presidents could blame other global factors, it's clear in this case that Trump owns the war.
And Iran's unwillingness to open the Strait of Hormuz shows he can't dictate events like he's used to.
"If the strait stays closed, he could be in deep trouble in the election," says Desmond Lachman, a senior fellow at the American Enterprise Institute and former International Monetary Fund official. "Iran knows it can cause real damage to the economy before the election."
Nearly eight in 10 Americans say gas prices are straining their household budgets, according to a PBS/NPR/Marist poll last month.
Context: The Republican-controlled Congress approved a housing affordability bill that Trump panned. Otherwise, the GOP has little to point to on the subject of voters feeling squeezed by higher prices.
Trump has fixated on unproven allegations of voter fraud, rather than inflation and the economy.
"I think oil is going to be a little bit of a yo-yo. Goes up a little bit, goes down a little bit," Trump told Fox Business last week. "And when this is over oil is gonna drop like a rock."
Yes, but: The status of the war changes constantly. With almost four months until the election, conditions in Iran could shift in a way that causes gas prices to fall again in time for Republicans to benefit.
"Long-term trends matter, but short-term trends also matter," Krosnick says.
The bottom line: As gas prices go, so may GOP hopes in the midterms.