Sen. Bernie Sanders (I-Vt.) on Wednesday said legislation that could soon come to the floor of the U.S. Senate would undermine efforts in states around the country to help Americans stay informed about what goes into their food.

“The American people have a right to know what they’re eating,” Sanders said during a press conference on Capitol Hill. “That is why states like Vermont, Maine, Connecticut and Alaska have adopted laws to label goods containing GMOs and why many other states are interested and on the path to do that.”

In 2014, Vermont became the first state in the country to mandate labeling for food that contains genetically modified ingredients. The law went into effect last Friday. Due in part to the state’s bold action, many large companies such as Campbell’s, Frito-Lay, Kellogg, and ConAgra are already labeling their products nationwide.

But legislation recently introduced by Sens. Debbie Stabenow (D-Mich.) and Pat Roberts (R-Kan.) creates a confusing, misleading and unenforceable national standard for labeling genetically modified food.

Instead of a uniform labeling standard like Vermont’s law, the bill allows text, symbols or an electronic quick response code to be used. The bill also contains huge loopholes and imposes no federal penalties whatsoever for violating the labeling requirement. If it becomes law, the legislation will preempt Vermont’s standard and create chaos for other states that have passed similar bills.

“The timing of this legislation is not an accident,” Sanders said. “Its goal is to overturn and rescind the very significant legislation passed in the state of Vermont. I will do everything that I can to see that it’s defeated.”

The leaders of Earthjustice, Greenpeace USA, the League of Conservation Voters, the Natural Resources Defense Fund and the Sierra Club on Tuesday sent a letter to senators in opposition to the Stabenow and Roberts’ bill. “We urge senators to heed the call for greater transparency, equitable access to information and protecting our right to know whether the foods we are eating and feeding our families contain genetically modified ingredients by opposing this bill,” the organizations wrote. Consumers Union, Just Label It, Center for Food Safety and Food & Water Watch also oppose the bill.

The Environmental Working Group has calculated that food and biotech companies and trade associations have spent nearly $200 million to oppose state GMO labeling ballot initiatives such as Vermont's. When combined with Washington lobbying expenditures that mention GMO labeling, the total amount spent by labeling opponents is close to $400 million.

Sanders was joined at the press conference by Sens. Patrick Leahy (D-Vt.), Jeff Merkley (D-Ore.), Jon Tester (D-Mont.) and Richard Blumenthal (D-Conn.).