WASHINGTON - Gas-station owners wouldn't be liable for problems caused by certain blends of ethanol fuel under a bill introduced Thursday by three Republican senators and one Democratic one.

The bill would block potential lawsuits related to E15, a gasoline blend with 15% ethanol that isn't approved for use in older engines or for storage in some underground tanks.

E15 isn't on the market yet, but the Environmental Protection Agency is moving forward with permitting it. Critics of that effort in the auto and refining industries worry about lawsuits stemming from engine damage or leaky tanks.

"This is really about giving customers more choice and better prices at the pump by empowering retailers to market multiple fuels using the same equipment," said Sen. John Hoeven (R., N.D.), the bill's lead sponsor, in a statement. Sens. Roy Blunt (R., Mo.), Amy Klobuchar (D., Minn.) and Mike Crapo (R., Idaho) also sponsored the bill.

Advocates of ethanol, which is made from corn and other materials, say that without E15, their industry won't be able to expand. Most current gasoline blends contain about 10% ethanol, but Congress has mandated that refiners use more ethanol in coming years and those refiners will likely have to break the 10% barrier to meet the requirement. Fuels with as much as 85% ethanol are available but aren't widely used.

The EPA has said E15 can be used in cars with model years 2001 and later. But older engines may not be able to handle the fuel without malfunctioning and the fuel could corrode some types of storage tanks.

In an unusual alliance, Thursday's bill had support from both the ethanol industry and at least one gasoline refiner.

The bill "would encourage the introduction of those higher blends of renewable fuel, only at levels approved by the federal government, while removing the threat of unwarranted litigation," Gregory Goff, chief executive of refiner Tesoro Corp., said in a letter Thursday to Hoeven.

Refiners, including Tesoro, generally oppose the government's efforts to mandate ethanol use.

Renewable Fuels Association President Bob Dineen said the bill "is a thoughtful approach that will help speed this country's transition to E15, higher ethanol blends, and other advanced biofuels," according to Hoeven's press release.

The bill would also require EPA to outline new criteria for equipment that can handle both E15 and other fuel blends.

Rep. John Shimkus (R., Ill.) Thursday was negotiating a companion bill in the House, his spokesman said.