As the nation's first GMO labeling law takes effect, food policy experts are warning that its benefits could be "fleeting," should the U.S. Senate pass a so-called "compromise" bill this week that would nullify Vermont's historic law as well as other state efforts in the works.

Vermont's law (pdf) requiring food manufacturers to clearly state whether a product is "produced with genetic engineering" went into effect Friday.

"Vermont had the courage to say, 'If it's the right thing to do, what are we waiting for,'" Democratic Gov. Peter Shumlin told a rally of about 150 people on the Statehouse steps. He asked supporters of the law to celebrate on social media under the hashtag #WeLabeledGMOS.

“But this victory may be fleeting," cautioned Wenonah Hauter, executive director of Food & Water Watch. "The Senate will vote next week on a federal bill that would nullify Vermont's law, and other state labeling efforts percolating, thanks to the heavy hand the ag-biotech industry wields over our congressional representatives."

Republican chairman of the Senate Agriculture Committee Pat Roberts, of Kansas, and ranking Democrat Debbie Stabenow, of Michigan, announced the so-called "compromise" bill—which has less stringent requirements—last month. Food safety advocates have decried the legislation (pdf) as anti-consumer, inadequate, and "inherently discriminatory."

As Hauter wrote in an op-ed on Friday:

Advocates of GMO labeling have pushed for clear, on-package language, just like what’s required under the Vermont law. But the Senate bill would allow manufacturers to post “call for more information” phone numbers or even smart phone “QR codes” if they so desire—meaning that if you have a phone with the right app installed, a steady hand and a solid data connection you’ll be able to access a website that will tell you what’s in the food you’re buying. That’s not a label—that’s a hassle.

Sen. Bernie Sanders (I-Vt.) last week called it "bad federal legislation" and vowed to do what he can do defeat the bill, which is expected to come up for a vote this week. He tweeted to that effect on Sunday:

People have a right to know what is in the food they eat and the Senate shouldn't stop states from passing laws that let that happen. — Bernie Sanders (@BernieSanders) July 3, 2016

The Minneapolis Star Tribune notes: "If the new bill passes the Senate, it must still pass the House, which earlier voted for a bill that places a national ban on on-package GMO disclosure."

It's a race against the clock, one industry lobbyist told Capital Press. "If Congress does not pass this bill by the 15th [when it goes on recess until after Labor Day], it won’t get taken up until September, which is much, much, much too late," said Roger Lowe, executive vice president of strategic communications for the Grocery Manufacturers Association.