WASHINGTON - U.S. wholesale inflation surged last month. Producer prices climbed 6% from a year earlier, the most since December 2022, fueled by the 10-week Iran war that drove up energy costs and squeezed companies into passing higher expenses to shoppers.

The Labor Department said Wednesday its producer price index - tracking inflation before it reaches store shelves - jumped 1.4% in April, the largest monthly rise since March 2022.

Energy prices rose 7.8% from March to April and 22.7% year over year. Gasoline prices leaped 15.6% month to month, while diesel - the key fuel for trucking and distribution - vaulted 12.6%.

Excluding fluctuating food and energy, core producer prices increased 1% from March and 5.2% from April 2025.

All figures far exceeded economists' projections.

Wholesale prices signal potential shifts in consumer inflation. Economists track them because components like health care and financial services feed into the Federal Reserve's preferred gauge - the Commerce Department's personal consumption expenditures, or PCE, price index.

On Tuesday, the Labor Department reported its key consumer price index rose 3.8% last month from April 2025 - the biggest annual gain in over three years - with energy prices still climbing.

Inflation is building as Americans chafe under soaring living expenses. Affordability will likely dominate voter concerns on Nov. 3, as they vote on whether President Donald Trump's Republicans hold the Senate and House.