Call it a blended decision. A long-awaited ruling by President Obama's Environmental Protection Agency (EPA) to permit 15 percent ethanol blends in cars, boats and trucks became a non-decision Tuesday, when the EPA decided not to decide. This makes some ethanol boosters happy, because at least the agency didn't say no. Others aren't so pleased, because a step up from the 10 percent blend available to motorists now is critical to the slumping industry's future growth. Corn growers in ethanol-pioneering Minnesota, with 17 ethanol plants, have been bird-dogging this decision all year. State officials want to jump up to a 20 percent blend. But an odd coalition of environmentalists, oil industry interests, and manufacturers has been standing in the way, urging a go-slow approach on heavily-subsidized ethanol. The critics argue that ethanol's benefits have been oversold, while its downsides have been overlooked. The EPA -- the folks who brought us E10 -- has been caught in the middle. On Tuesday, it issued a letter calling for more study, but it added these words of encouragement: "Robust fuel, engine and emissions control systems on newer vehicles (likely 2001 and newer model years) will likely be able to accommodate higher ethanol blends, such as E15." Growth Energy, the coalition of U.S. ethanol supporters that filed the E15 request, described the statement as a "strong signal" that the EPA is preparing to approve E15 upon the completion of ongoing tests early next year. But the industry's main lobby in Washington, the Renewable Fuels Association (RFA), isn't smiling. Said RFA president Bob Dinneen: "This delay threatens to paralyze the continued evolution of America's ethanol industry…In order to avoid paralysis by analysis, EPA should immediately approve intermediate ethanol blends, such as E12. Allowing for a 20 percent increase in ethanol's potential share of the market would provide some breathing room for the industry while EPA finishes its testing on E15." Tuesday afternoon update: Sen. Amy Klobuchar, D-Minn., wrote EPA administrator Lisa Jackson today urging her to take swift action to promote biofuels like ethanol. "Moving to a higher ethanol blend is an important step in decreasing our country's dependence on foreign energy," she said. "The faster we do this, the faster we can strengthen our economy and create jobs."