Republican and Democratic leaders on the Senate environment committee said they are on the fence about a bill to allow year-round blending of 15-percent ethanol fuels.

Sen. John Barrasso, R-Wyo., chairman of the Environment and Public Works Committee, said Wednesday that his state does not support the higher E15 blends, but is willing to listen to the bill's supporters.

"In Wyoming, folks want fuel with less, not more, ethanol," said Barrasso, noting the harmful effects ethanol has on small engines. "No one should be surprised that I don't support [the bill]," he said. "But [it] deserves a full and fair hearing before this committee."

The bill would allow the higher ethanol-to-gasoline blends to be made available during the summer. Environmental rules prevent 15-percent ethanol blends from being blended during the summer because of the fuel's Reid Vapor Pressure, a measure of fuel volatility.

Sen. Tom Carper, D-Del., the panel's ranking member who supports renewable fuels, also did not come out to support the bill, citing a backroom deal in which Midwest lawmakers struck an agreement to hold a hearing on the ethanol bill in exchange for their support on an unrelated bill.

"I have not made commitments," Carper said, because he was not privy to the agreement that was cut. He too said he would wait to hear more from the bill's supporters and detractors before deciding how to vote. Carper wasn't against the deal that was cut and even applauded it as an example of ways to gain support between Republicans and Democrats on clean energy issues.

Carper told Barrasso he will mark him down as "undecided." Barrasso quipped that he was undecided, "but still your friend."

The E15 bill would help advanced biofuel producers meet the next phase of the Environmental Protection Agency's Renewable Fuel Standard, which must begin blending more ethanol not derived from corn. The fuel market for ethanol is saturated and unable to adequately blend more advanced forms of ethanol derived from plant waste, or cellulose.

Cellulosic ethanol proponents testifying Wednesday said advanced ethanol is now commercially available, but it requires a much larger market. The 15-percent blends would expand the market from the current 10-percent blends that dominate the market using primarily corn ethanol.

Barrasso also said the Renewable Fuel Standard "is broken and EPA is not in a place to fix it."

Carper, whose state of Delaware has a number of oil refiners, also raised issues with the EPA fuel program, which has created uncertainty for some of the smaller refiners through volatility in a credit program they use to comply with the mandate.