“It doesn’t make sense to provide people with a tax subsidy to encourage people to do what they would otherwise do at any rate,” Mr. Bingaman said. “The fact that we have budget problems is making the need to phase out or eliminate the tax credit that much more urgent.”

Many economists say an end to the blender’s tax subsidy would have minimal impact.

“In the short term, six to nine months, we might see a minor reduction in production,” said David A. Swenson, an economist at Iowa State University. “But within a year or so, we would expect production to climb back to where it is right now because we still have the mandate, which guarantees demand and maintains the price level of ethanol.”

As for the tariff — a 54-cent-a-gallon tax on imported ethanol first imposed in 1980 — analysts say it is unnecessary now because Brazil, generally a leading source, is tightening production. Brazilian refiners make ethanol from sugar cane, but with sugar prices high on international markets, they are making less ethanol and more sweetener.

Mark Marquis, president of Marquis Energy, which operates two ethanol plants in Illinois and Wisconsin, said the industry understands that times have changed.

“We don’t need the blender’s credit,” said Mr. Marquis, who is also a director of Growth Energy, an ethanol lobbying group. “It’s time that it goes away.”

But that does not mean the ethanol industry wants to give up the money entirely.

The fuel blending mandate has resulted in a standard of 10 percent ethanol mixed into gasoline sold at most service stations in the country. But with gasoline demand essentially flat, so is demand for ethanol.

In January, the Environmental Protection Agency said cars and light trucks built since 2001 could safely use a blend with up to 15 percent ethanol, although few stations are now equipped to supply that. So the ethanol industry now wants the government to help it grow by subsidizing gas pumps.