U.S. average retail diesel prices fell below $6 a gallon on Saturday after remaining above that level for two months, reaching $5.998, according to GasBuddy. Prices declined from a record $6.519 on September 22 as seasonal demand weakened, refinery maintenance largely ended and Brent crude futures fell 18.5% over the previous two weeks. Diesel had surged after the US-Israeli war against Iran disrupted oil supplies and Ukraine's systematic attacks on Russian refineries stymied production. Higher diesel costs, which feed into transportation and freight expenses, increased inflationary pressure on consumers, farmers and businesses and were described as a major factor helping Democrats sweep both houses of Congress from President Donald Trump's Republicans in this month's midterm elections. California prices briefly exceeded $10 a gallon because of constrained refining capacity and stricter fuel specifications. Trump administration measures, including temporarily lifting federal taxes on red-dyed diesel, easing sanctions on Russian fuel and launching an $8 billion program to help farmers offset higher autumn-harvest fuel costs, provided limited relief while supply concerns linked to the ongoing Iran war persisted. Gasoline also fell below $4 a gallon this month for the first time since August 10.