California Democratic Sen. Barbara Boxer co-authored an amendment that would permit states to require special labels on genetically modified foods. An Oregon Democrat would exclude industrial hemp from the definition of marijuana, while a Nevada Republican would prohibit members of Congress from receiving federal crop payments.

Twenty-three current members of Congress -- six Democrats and 17 Republicans -- have received any farm payments since 1995, according to a database of the nonprofit Environmental Working Group. Many of these payments were small, such as California Democratic Rep. Jim Costa’s reported partial share of a $2,494 payment several years ago.

“Every effort should be made to ensure that members do not take advantage of their elected office for financial gain,” Sen. Dean Heller, R-Nev., intoned upon introducing his lawmaker subsidy amendment late last week.

Feinstein’s henhouse amendment addresses heftier policy issues, and its fate is uncertain, even though it already has the public backing of at least a dozen other senators.

The amendment adopts a compromise reached by the United Egg Producers and the Humane Society of the United States. In 2008, the two organizations had fought over California’s Prop. 2, which requires more living space for egg-laying hens, pregnant pigs and calves raised for veal starting in 2015. Voters approved the ballot measure, which has spurred movements in other states.

The industry typically provides 67 to 87 square inches of living space for each egg-laying hen. The Feinstein amendment would phase in over the next 18 years a requirement to increase the minimum living space to 124 to 144 square inches per hen. The industry would gain the advantage of pre-empting more aggressive state efforts.

“The egg industry brought this legislation to Congress and has asked us to help them implement the uniform regulations needed to survive and grow," Feinstein said last month in a Senate speech.

Support for the proposal is widespread, but not uniform. Bradley Miller of the Humane Farming Association, based in the San Francisco area, called the measure “a direct assault upon egg-laying hens, voters and states’ rights" and claimed it still would provide too little living space. Pork producers, among others, also have worried that the national henhouse standards could become a burdensome precedent for other industries.

The Senate is expected to debate the farm bill and its myriad amendments for another week or two. The House of Representatives hasn’t yet taken up its version.