Lawmakers are preparing for a second run at writing the new U.S. farm law that ended in a stalemate in 2012, and the biggest obstacle is not likely to be soil conservation or crop subsidies, but the billions spent mostly in cities and towns.
Analysts say food stamps for the poor, the biggest Agriculture Department program at an estimated $79 billion this year, is the make-or-break issue. Republicans are demanding far larger cuts than Democrats will entertain, and the debate is becoming increasingly partisan.
Enrollment in the program has doubled in a decade and costs have tripled. Critics say spending is out of control when only the neediest should get aid. Defenders say the weak economy is the culprit - enrollment is highest during economic turmoil - and that food stamps are targeted to avoid cuts in farm subsidies.
Food stamps "is the key to getting a final farm bill done. Not that there won't be plenty of other fights," said Pat Westhoff, director of the Food and Agricultural Policy Research Institute (FAPRI), a think tank at the University of Missouri.
"It seems like there is going to be some trimming and a battle between the House (of Representatives) and Senate over how much," said analyst Mark McMinimy of Guggenheim Securities. "I think a lot of heat is going to be around nutrition assistance."
The Senate Agriculture Committee is scheduled to start drafting its bill on Tuesday, with its House panel likely to follow on Wednesday. "On food stamps, they're going to be 10 miles apart," said a farm lobbyist.
Democrat Debbie Stabenow of Michigan, who chairs the Senate Agriculture Committee, is aiming for $4 billion in food stamp cuts over 10 years.
That is a far cry from the $20 billion in savings targeted by Oklahoma Republican Frank Lucas, the House Agriculture chairman, up $4 billion from the proposal in last year's bill, which House Republican leaders never put to a floor vote.
Republicans such as Senators Pat Roberts of Kansas and John Thune of South Dakota, and Representatives Marlin Stutzman of Indiana and Randy Neugebauer of Texas, would cut food stamps much more deeply, by some $36 billion over a decade.
While Stabenow says closing loopholes can generate substantial savings, the Republican faction would restrict eligibility broadly.
Between 2 million and 4 million people could be cut from the program under the Republicans' cuts, says an anti-hunger expert. That would be as much as 8 percent of the current enrollment.
Those receiving food stamps - formally known as the Supplemental Nutrition Assistance Program, or SNAP - was a record 47.8 million at the end of 2012, up from 46.5 million a year earlier.
Agriculture Committee leaders from both chambers commonly say farm policy is not a partisan issue.
Historically, disputes have split along regional lines that pit cotton and rice growers from the South against corn and soybean farmers of the Midwest. Republicans and Democrats cooperate based more on geography than party affiliation.
On food stamps, party identification increasingly appears paramount, however.
While Senate Agriculture Committee members Roberts and Thune, from the socially conservative Great Plains, want to cut food stamps, another committee member, Democrat Kirsten Gillibrand of New York, circulated a letter opposing any cuts in food stamps. It was signed by 32 Democratic senators.
In the House, Massachusetts Democrat Jim McGovern has sponsored a resolution opposing against food stamp cuts. As of Wednesday, it had 115 sponsors, all Democrats.
The farm bill died in the House at the end of 2012 in an election-year deadlock over food stamps. The Democratic-led Senate passed its version over the summer.
Small-farm activist Ferd Hoefner, policy director at the National Sustainable Agriculture Coalition, said the quarrel over SNAP could rupture a long-standing partnership of rural and urban lawmakers who supported farm programs on the one hand, and public nutrition programs on the other.
"Is this the end of the farm bill coalition?" Hoefner said.