WASHINGTON (AP) — The largest monthly jump in gas prices in six decades caused a sharp spike in inflation last month, creating major challenges for the inflation-fighters at the Federal Reserve and heightening already substantial political hurdles for the White House.

Consumer prices rose 3.3% in March from a year earlier, the Labor Department said Friday, up sharply from just 2.4% in February and the biggest yearly increase since May 2024. On a monthly basis, prices rose 0.9% in March from February, the largest such increase in nearly four years.

It’s the first read on inflation to capture the effects of the Iran war. The surge in gas prices will stretch the budgets of lower- and middle-income households as it erodes their incomes, making it harder to afford other necessities such as food and rent.

Excluding volatile food and energy, core prices rose 2.6% in March from a year earlier, up from 2.5% in February. And last month core prices rose a modest 0.2%, suggesting that rising gas prices haven’t yet spread to many other categories.

A big question for now is how long the oil and gas price shock lasts and whether it will lead to a broader, long-lasting inflation boost, similar to what occurred in the spring of 2022 after Russia invaded Ukraine. For now, economists say that it is unlikely the U.S. will see a widespread increase similar to a few years ago, when inflation topped 9%.

Still, how the war and its impact on inflation will play out in the coming months remains highly uncertain. Despite a tenuous cease fire, little has changed in the Strait of Hormuz, a bottle neck where millions of barrels of oil typically pass daily.

“It’s painful in the near term,” said Michael Pearce, chief U.S. economist at Oxford Economics. “It’s going to get more painful in April,” when further gas price increases will lift inflation higher.

But Pearce said the impact may be shorter-lived than after the pandemic: “I think the conditions are much more like a short, sharp shock than what we saw in 2022.”

Industries that depend on oil and gas are paying more, particularly airlines, which have passed on those higher costs to travelers. Fares jumped 2.7% just last month and are 14.9% higher than a year ago. Many delivery services, including UPS and FedEx, have already announced fuel surcharges that have raised shipping costs for businesses and households.

Grocery prices slipped 0.2% last month and are up just 1.9% from a year earlier, yet economists believe they will move higher in the coming months as diesel fuel prices surge. Most food is shipped by truck.

More expensive fuel is “contributing to rising production costs across the food supply chain and could put upward pressure on grocery prices going forward,” said Andy Harig, a vice president at the grocery trade group FMI-The Food Industry Association. “As energy prices increase, the costs associated with producing and delivering food also rise.”

Clothing costs rose 1% in March from the previous month and are up 3.4% from a year earlier. Used car prices, however, fell 0.4% last month and down 3.2% from a year earlier.

The gas price shock stemming from the Iran war has shifted inflation’s trajectory, from a slow, gradual decline to a sharp increase further away from the Fed’s 2% target. As a result, the central bank will almost certainly postpone any cut in interest rates for months. Many Fed officials will look past the increase in headline inflation, however, and focus on core prices, which are likely to rise more slowly.

If Americans cut back on spending elsewhere in response to more expensive gas, the economy could slow and unemployment may rise.

Consumer sentiment plunged to a record low in April, according to a survey released Friday by the University of Michigan, largely because of the Iran war and concerns over higher gas prices. Their Index of Consumer Sentiment fell to 47.6, from 53.3 in March.

“Many consumers blame the Iran conflict for unfavorable changes to the economy,” said Joanne Hsu, the university’s director of consumer surveys.

High prices had angered American voters before the war and the spike in prices for oil and everything that entails, from the pump to the grocery store, could make it more difficult for the president’s party to hold on to seats in both the House and the Senate in this year’s midterms.

Polling by the Associated Press-NORC Center for Public Affairs Research last month found that about six in 10 Republicans are at least “somewhat” concerned about affording gas in the next few months.