One unexpected price surge most Americans don’t see is raising the stakes for Trump before November

The fuel most Americans rarely think about is becoming a new hurdle for President Donald Trump’s push to make housing more affordable, as the Iran war raises costs for construction sites.

With the midterm elections approaching, the diesel surge underscores the political tension facing Trump and congressional Republicans as they promise to bring down housing costs while war-driven energy prices add new pressure to home construction.

Builders are already wrestling with expensive financing, labor, materials and costs tied to regulations and permitting that Republicans have pledged to reduce. Because diesel powers the trucks and heavy equipment used throughout the construction process, higher prices can make it harder to deliver the lower-priced homes needed to ease America’s affordability crunch.

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Jim Tobin, president and CEO of the National Association of Home Builders (NAHB), told Fox News Digital that diesel is "critical to construction."

"Diesel, which our workers use when they're hauling materials on trucks and moving dirt on sites, has seen a spike, and that has really put a little bit of pressure on home building in the short term here."

Unlike gasoline, which is felt most directly by motorists, diesel powers the trucks hauling lumber, concrete, appliances and other supplies to construction sites, as well as the heavy equipment that prepares lots and builds new homes.

The national average price of on-highway diesel climbed to $5.65 a gallon this week, up nearly $2.00 from a year ago, according to data compiled by the Energy Information Administration. Diesel's year-over-year increase has been far sharper than gasoline’s, with the national average for regular gas at about $4.09 a gallon.

The added pressure comes as Trump has made housing affordability a key part of his second-term agenda. In March, he signed an executive order directing federal agencies to reduce regulatory barriers that raise construction and homeownership costs, with an emphasis on speeding permitting and expanding supply.

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But even as the administration targets regulatory costs, builders say other expenses can quickly offset those savings.

Tobin said the industry has so far seen only a modest impact from tariffs on construction inputs. But he has begun hearing from manufacturers announcing price increases, particularly those tied to steel and aluminum costs. Diesel adds another layer of pressure by raising the cost of both getting materials to a job site and completing the work once they arrive.

The issue is especially significant in fast-growing states across the South and Southwest, where an influx of residents, businesses and capital has fueled demand for new housing.

"States that find themselves ahead of the curve are planning those two critical components, infrastructure and housing, together," Tobin said. "They’re going to be better prepared for growth in the future."

Builders are also grappling with a persistent shortage of construction workers. Tobin said the industry is roughly 250,000 workers short, raising labor costs and contributing to project delays.

More homes are needed to ease price pressures, but each increase in the cost of labor, land, materials, financing or fuel makes that task harder. Diesel may not appear on a buyer's closing documents, but its cost can still be felt long before they get the keys.

The White House did not immediately respond to Fox News Digital's request for comment.