The chances of the U.S. Congress passing a five-year farm bill by year's end are a little better than 50/50 given the gridlock over food stamps for the poor, a top farm policy expert said on Monday.

Congress has about 50/50 chance of passing farm bill in 2013 "There is a slightly better chance than 50/50 that we will get a bill rolled into a budget at the end of the year. But it's no better than that," Barry Flinchbaugh, a Kansas State University agricultural economist who advises legislators shaping the U.S. farm bill, told Reuters on the sidelines of a farm bankers meeting in Minneapolis.

The farm bill, already a year behind schedule, is the master legislation that directs government supports for farmers and food aid programs.

The bill is now with a conference committee of 41 members of Congress who are hammering out the difference between the House and Senate bills. The biggest difference: the Senate wants $4 billion cut from food stamps while the House wants to reduce the program by $40 billion.

"Food is the only division. The other issues can be settled," said Flinchbaugh, citing variations in how they address crop insurance for farmers along with other subsidies.

Historically, the conference committee reconciles differences and brings a compromise to a final vote. That process has been hampered by the deep divisions between the Republican-controlled House and the Senate, where Democrats are in the majority.

"There is a way perhaps we can get past this food stamp gridlock. We cut food stamps $6-$8 billion and then we put in all these caveats the far right wants to put in the food stamp program, like work requirements and drug tests," said Flinchbaugh, who has advised on farm policy for over 40 years.

The government extended the expired 2008 farm bill last year. Leaders of the House and Senate agricultural committees have a self-imposed deadline of reaching agreement by Thanksgiving and the White House has threatened to veto a bill with large food stamp cuts.

If Congress fails to pass a new bill, a second extension is likely, Flinchbaugh said.

"There is some talk we will do that for two years because we don't want to be messing with this during an election year," Flinchbaugh said. "Or, we implement the permanent legislation."

Without a new law, U.S. farm policy will be dictated by an underlying 1938 permanent law that would bring back the concept of "price parity" which led to sharply higher guaranteed crop prices, Flinchbaugh said.

"It's normally been the safeguard to push the Congress to act," Flinchbaugh said. "But I've never seen a Congress like this one. So it's very hard to predict."

"Consumers are the biggest losers without a farm bill," he added.

Given the impasse on this farm bill - which traditionally has had bipartisan support - some farm analysts are suggesting this could be the last farm bill, ending 80 years of U.S. farm policy designed to protect farm price and income.

"If we remove food and nutrition bills from the farm bill this is the last one," Flinchbaugh said. "If we keep the consumer-farmer coalition together there will be future farm bills."

"There are 400 urban districts in the House of Representatives and 35 rural districts. When you're a minority like farmers - granted they are a potent minority because they produce food - but you remove nutrition and food stamp programs from the farm bill, the leverage is over.

"Another thing, if you take food stamps and nutrition programs out of the farm bill you're removing about 85 percent of USDA's budget. Can USDA survive with 15 percent of its budget? Likely not," Flinchbaugh said.