The Senate is seeking to reverse a controversial law that allows farmers to harvest genetically modified crops even when the crops are caught up in legal battles.
The law was passed as part of a spending bill earlier this year and has become a flashpoint in the national debate over genetically engineered foods.
It would expire at the end of the federal budget year, on Monday, and a temporary spending bill passed by the House would extend it. But Senate Democrats' spending bill would let it expire.
The provision applies to crops that are under litigation. It allows the agriculture secretary to permit farmers to continue growing engineered crops while appeals are pending, even if courts have ruled that Agriculture Department shouldn't have approved them.
Explore further: IBM and Mars join together to make food safer with genetics