The Energy Information Administration (EIA) said national prices for regular unleaded gasoline fell 26 cents over the last week to $2.40 a gallon, down 61 cents from a year ago.

Gasoline prices have been falling rapidly as crude oil prices have declined on slowing demand and the global economic crisis.

Over the summer, fuel prices became a major issue in the U.S. presidential campaign, as gasoline prices surged to a record $4.11 in July.

But with gasoline prices plummeting, experts said energy costs may be a lower priority for voters on Tuesday.

"I suspect that those polls will find that gasoline prices will be nowhere near as important to voters...as they were in July and August," said Jerry Taylor, an energy expert at the Cato Institute.

"The oil price crash and related gasoline price declines are one reason. But the other is that the financial crisis has swamped all other domestic economic issues in importance," he added.

The average price of gasoline fell in every region of the country.

Gasoline was most expensive on the west coast at $2.74, down 31 cents. San Francisco had the highest big city price at $2.89.

The Gulf coast had the lowest regional price at $2.23 a gallon, down 23.2 cents. Houston had the lowest pump price at $2.11, down 30 cents.

The EIA also reported gasoline prices were down 28 cents at $2.63 in Chicago; down 34.9 cents at $2.85 in Los Angeles; down 24.4 cents at $2.54 in Seattle; down 25.5 cents at $2.38 in Denver; down 18 cents at $2.65 in Miami; down 19.4 cents at $2.54 in New York City; down 20.6 cents at $2.39 in Boston; and down 35.4 cents at $2.12 in Cleveland.

Separately, the average price for diesel fuel fell 20 cents to $3.09 gallon, down 21.5 cents from a year ago, the EIA said.

The New England states had the most expensive diesel at $3.42 a gallon, down 15.3 cents. The Midwest had the cheapest diesel at $3.02 a gallon, down 22.6 cents.

(Reporting by Ayesha Rascoe; Editing by David Gregorio)