“Agriculture has always been bipartisan,” Ms. Stabenow said. “But the extreme element of the House doesn’t believe” in a farm bill at all, she said, while others “don’t want reforms.” She added, “The anti-reformers are hiding behind the extreme elements.”

Some Republicans are now pondering a one-year extension of the current law. Democrats in both chambers have declined to entertain that idea for now.

Just outside the Capitol on Wednesday, the National Farmers Union and the American Farm Bureau Federation held a modest rally to press for the approval of a bill, and lawmakers appealed to them with folksy talk about tractors.

Lynn Belitz, a farmer from Nebraska who attended, said, “They should just get it done.”

Some Democrats are trying to press the House leadership to allow a vote through something called a “discharge petition,” which, if signed by 218 members, would force a floor vote. But it is being held up by procedural impediments.

“I’ll sign it as soon as it’s available,” said Representative Kristi Noem, a Republican freshman from South Dakota. When it was pointed out to her that this would probably greatly dismay Republican leaders, she added, “I take my orders from my district.”

Some liberal Democrats said that though they opposed even modest cuts to the food stamp program, they would support the House bill because they assumed its cuts would be reduced somewhat during negotiations over the final bill. They also reason that should Mitt Romney prevail in the November presidential election, larger cuts to nutrition programs would most likely be in the offing.

“This is far from a perfect bill,” said Representative Peter Welch, Democrat of Vermont. “But we should vote up or down on this bill, and then we can be held accountable. We could be in a worse position next year, including on food stamps.”