WASHINGTON – Fighting an uphill battle to require better gas mileage on sport utility vehicles, vans and light trucks, Sen. Olympia Snowe and like-minded colleagues have latched onto a new argument: Raising federal standards on fuel efficiency will strengthen national security.

Because the U.S. war on terrorism heightens the potential for instability in the oil-rich Middle East, Snowe, R-Maine, warned that reducing dependence on foreign oil has become more critical than ever.

The United States imports more than half of its oil and petroleum products, “from the most unstable region of the globe,” Snowe told members of the Senate Committee on Commerce, Science and Transportation on Thursday.

“The bottom line is, the fastest, cheapest and cleanest step toward reducing our dependency on foreign oil is to increase the fuel efficiency of our biggest gas guzzlers – SUVs and minivans,” she said.

Snowe is a chief co-sponsor of legislation aimed at raising the average gas mileage of SUVs, vans and light trucks from 20.7 miles per gallon to 27.5 miles per gallon by 2007 – the same gas mileage required of other vehicles such as sedans and station wagons.

The move would save 1 million barrels of oil a day and cut dependence on foreign oil by 10 percent, supporters say.

Light trucks now are considered commercial vehicles under the 1975 law known as the corporate average fuel economy, or CAFE, standards, approved by Congress after the economically debilitating Arab oil embargo.

“Back then, the term ‘SUV’ hadn’t even been coined,” Snowe noted, adding that the soaring demand for such vehicles soon is expected to exceed the number of passenger vehicles sold nationwide, a feat already achieved in 36 states last year.

“In short, the SUV loophole has not only become an anachronism, but also an unnecessary threat to our environment and even to our national security,” Snowe said.

She also predicted that added fuel efficiency would save consumers money at the gas pump.

Environmental groups have voiced strong support for the legislation because they see fuel economy as the best way to cut down on the auto emissions and help curb global warming.

“We would liked to see it adopted – as a first step,” said David Doniger of the Natural Resources Defense Council, an organization calling for a 40 mpg standard on all passenger vehicles by 2012.

Hopes are that Snowe’s measure, co-sponsored by Sen. Dianne Feinstein, D-Calif., will be attached to a sweeping energy package expected to reach the Senate floor early next year.

Although the two lawmakers have the blessing of Senate Majority Leader Tom Daschle, D-S.D., they still face a tough battle. Similar legislation met overwhelming defeat in the House last August when Democrats representing auto-producing states joined Republicans to derail it.

The Alliance of Automobile Manufacturers, a trade group, calls the CAFE standards a failed program because it does not consider consumer demand.

“The top 10 fuel-efficient vehicles we manufacture account for less than 2 percent of all vehicles sold in the United States,” said Eron Shosteck, spokesman for the organization.

Shosteck said that backers of fuel efficiency are misdirected. “The future is in alternative technology such as hybrid electrical vehicles and fuel cells,” he said.

The White House also has signaled concerns that more strict CAFE standards could affect motorist safety if manufactures feel compelled to make vehicles with lighter – and weaker materials.

Lighter vehicles developed during the 1970s and 1980s “probably resulted in an additional 1,300 to 2,600 traffic fatalities in 1993,” according to a July report from the National Academy of Sciences.

CAFE gives the National Highway Traffic Safety Administration a free hand to set average gas mileage standards for light trucks, but sets the level for passenger cars at 27.5 mpg.

For six years, Congress has barred NHTSA from considering an increase in the fuel economy standards, but that prohibition was not included in the transportation-spending bill the Senate passed on Tuesday.