WASHINGTON — A bill to create the first nationwide labeling standard for genetically modified foods is getting push-back from consumer advocates alarmed that its language could exempt a vast majority of foods made with genetic engineering.

“There may be no genetically engineered food that we commonly eat that’s actually covered by this law as it’s currently written,” said Jean Halloran of Consumers Union, the policy arm of Consumer Reports. “I have to think that that’s a drafting error, but nobody’s said they’re going to fix it.”

The bipartisan compromise bill, negotiated last month by the Republican chairman of the Senate Agriculture Committee, Pat Roberts of Kansas, and the panel’s top Democrat, Sen. Debbie Stabenow of Michigan, is on the verge of passing the U.S. Senate this month. Next it will go to the U.S. House of Representatives, where it’s expected to face little resistance.

The bill would require producers to identify foods that contain genetically modified ingredients with text on packages, a symbol or a link to a website with a QR code, a bar code that can be scanned on a smart phone.

But the legislation contains several sentences that “raise confusion,” according to a June 27 memo to lawmakers from the Food and Drug Administration, which has long maintained that GMOs are safe to eat, and therefore do not need to be labeled.

In the memo, the FDA noted that one paragraph in the Roberts-Stabenow bill narrowly defines bioengineered food as containing “genetic material,” which could exclude many products made from bioengineered crops, such as refined sugars, oils and starches.

The bill’s language also would limit coverage to foods where the genetic modification “could not otherwise be obtained through conventional breeding or found in nature,” a standard that could be hard to prove, the agency said.

Halloran said consumer groups are scrambling to bring lawmakers attention to these concerns before an expected vote July 13.

“It was brought forward so quickly without a hearing or much review, and it took us a while to tussle through what it actually says, so I think it hasn’t gotten the kind of serious scrutiny that it needs,” she said.

A coalition of nearly 70 consumer groups and organic farming associations has sent a letter urging senators to oppose the legislation, calling it “a non-labeling bill under the guise of a mandatory labeling bill.”

The letter estimates that 99 percent of all GMO food ultimately could be exempt from labeling since the bill leaves it up to a future Secretary of Agriculture to decide how much GMO content in a food qualifies it for labeling. “If that secretary were to decide on a high percentage of GMO content, it would exempt virtually all processed GMO foods,” the letter said.

Consumer advocates also object to the lack of consequences for companies that fail to properly label their products and the fact that the labels themselves won’t necessarily have to contain the words “GMO,” “genetically modified” or “biotechnology.”

Roberts defended the bill in a statement on Friday.

“All bioengineered food crops currently on the market are captured by the definition of ‘bioengineering,’” he said.

Whether that definition also captures refined sugars, oils and other products made from genetically engineered crops, will be determined through rule-making by federal agencies that implement the legislation, said Meghan Cline, a spokeswoman for the Senate Agriculture Committee.

The bill is likely to pass in the Senate, where it received 68 votes to overcome a procedural hurdle on Wednesday.

For those opposed to the Roberts-Stabenow bill, the fight has taken on particular urgency because the federal legislation would nullify any state laws that require GMO labeling.

The first such law in the nation went into effect in Vermont on Friday.

Fresh off the campaign trail, Vermont Sen. Bernie Sanders has vowed to do everything he can to defeat the Roberts-Stabenow bill.

From the steps of the statehouse in Montpelier, Vermont, on Friday, Sanders said he and other members of Congress would not allow Vermont’s law to be overturned by bad federal legislation.

Sanders said the Roberts-Stabenow bill “would create a confusing, misleading and unenforceable national standard” for GMO labeling.

The major agribusiness and biotech companies “do not believe people have a right to know what’s in the food they eat,” Sanders said. “That is why they have spent hundreds of millions of dollars in lobbying and campaign contributions to overturn the GMO right-to-know legislation that states have already passed and that many other states are on the verge of passing.”