Expressing the Republican view of the bill, Sen. Saxby Chambliss, who serves on the agriculture committee, described the proposed EPA regulations as "burdensome and duplicative" and said that they do "absolutely nothing to further protect or enhance the environment."
But it's not just Republicans who back the bill.
Debbie Stabenow of Michigan chairs the agriculture committee that passed the bill. Asked if she would attempt to bring the legislation to the floor over the objections of Cardin and Boxer, Stabenow said "it is my goal to see if we can't work with our colleagues to develop an agreement."
Cardin also said he hopes a deal can be reached.
But environmental and farming groups say there have been no substantive negotiations over the bill to date. Further, because the legislation is so narrowly crafted and responds to a court order, there is little middle ground on which a compromise could be struck -- the permits must either be required, or not.
That leaves supporters of the legislation with limited options: They can try to force a vote on the floor by rounding up the 60 votes needed to end debate on a bill, or they can try to stick the measure into some other piece of legislation that has a better shot of approval.
Rod Snyder, director of public policy with the National Corn Growers Association, said farming groups began rounding up votes earlier this year in anticipation of possible opposition.
"We believe that we have enough support in the Senate to get this done," Snyder said.
Scott Slesinger, the top lobbyist for the NRDC, said he isn't convinced that proponents have yet found the votes that would be needed to overcome Cardin's threatened filibuster -- but he acknowledged that they are close. Similar legislation often divides lawmakers not by party, but by whether or not they represent farm states.
The possibility of a showdown on the bill has prompted environmental groups like the NRDC to also step up pressure on lawmakers, he said.
"It's just appalling to say 'We're going to put more pesticides in the water,'" Slesinger said. "We're trying to get the word out -- in particular to people who would normally support environmental positions -- how awful this bill is."