By Thursday, more than 30 amendments had been filed to the 2012 Senate farm bill, ranging from a ban on support for ethanol blender pumps, to two approaches to limiting crop insurance premium subsidies, to increasing the bill's relatively small level of funding for beginning farmer programs.

Senator John McCain, a veteran critic of ethanol programs, has filed Senate Amendment 2163, described in the Congressional Record as "Prohibition on Use of Federal Funds Relating to Ethanol Blender Pumps and Ethanol Storage Facilities."

It's uncertain whether the amendment will be allowed a vote, but it makes industry groups like the Renewable Fuels Association uneasy. 

"Senator McCain never misses an opportunity to try to roll back the progress America's renewable fuels industry is making in helping this country become more energy and economically secure," said RFA president, Bob Dinneen  "Three out of four Americans say they want greater choice at the pump.  Amendments like this would deny the will of 75% of Americans and only lead to a greater dependence on petroleum and higher prices for fuel."

Two amendments take different approaches to limiting subsidies for farmers' crop insurance premiums. One, introduced by Senators Tom Coburn (R-OK) and Dick Durbin (D-IL), would reduce premium subsidies by 15% for farmers (or legal entities) with adjusted gross income above $750,000. The limit would start with the 2014 reinsurance year.

The other approach, backed by Senators Jeanne Shaheen (D-NH) and Pat Toomey (R-PA) would limit subsidies for farmer premiums to $40,000 per year.

“The Shaheen-Toomey amendment simply proposes the same payment limitations that have been applied to direct payments for years,” said Scott Faber, vice president of government affairs at the Environmental Working Group. “This makes perfect sense as crop insurance has become the primary farm safety net.”

The EWG said the $40,000 hard cap on subsidies, would save the federal government $5.2 billion over 10 years. The Coburn-Durbin approach cuts spending by about $1.2 billion. 

Both approaches are opposed by many farm groups, including the National Association of Wheat Growers, whose newsletter said Thursday: "If adopted, this amendment would limit participation in crop insurance and distort the risk profile of those who do participate. This change could also reduce the ability of producers to secure financing. Driving farmers out of the crop insurance program will reduce the overall safety net for U.S. farm production and could impair the ability of the program to function efficiently and effectively, leading to calls from farmers for supplemental disaster assistance in times of acute crisis."

The limits would not bar the largest farms from buying crop insurance, nor would they affect indemnity payments on losses.