House Republicans plan to propose a $40 billion cut to the nation's food stamp program, the head of the House Agriculture Committee said on Thursday, doubling the number of cuts previously sought by conservatives.

Committee Chairman Frank Lucas said legislation on the food assistance program, known as SNAP, would be the second part of any talks on the U.S. farm bill with the Senate.

Lucas told lobbyists during a lunch speech in Washington that a Republican working group agreed on cuts expected to total $40 billion and could include steps such as mandatory drugs tests and employment rules.

"The Republican leadership plans to bring up yet another political messaging bill to nowhere in an effort to try and placate the extreme right wing of their party," Collin Peterson, the ranking Democrat on the House Agriculture Committee, said in a statement.

In June the House defeated a farm bill that included $20 billion in food stamp cuts, primarily because conservatives wanted cuts as high as $100 billion.

The House on July 11 passed a farm bill that was limited only to agricultural support programs, leaving out food stamps altogether. The two elements are typically twinned, as they were in the Senate version that was passed in June.

Lucas said staff-level work toward reconciling the two chambers' bills would continue during the upcoming five-week congressional recess - pre-conferencing before formal negotiations between the House and Senate commence.

"I think we'll make great progress," he said.

The Senate bill called for $4 billion in cuts to the food stamp program.

Because of the huge difference between the two versions, "this may be one of those issues that ultimately needs a little guidance from on high," Lucas said, referring to Republican House Speaker John Boehner and Harry Reid, the Democratic Senate Majority Leader.

Lucas said it would be difficult to complete the bill before current farm law expires on September 30.

Later on Thursday Debbie Stabenow, Democratic chair of the Senate Agricultural Committee, plans to speak about "the path forward" for the farm bill.

Peterson said the additional food stamp cuts "effectively kills any hopes of passing a five-year farm bill this year."