AUGUSTA, Maine — Maine’s two congressional representatives don’t always see eye to eye but they joined forces this week against a proposed law that would ban states from requiring food manufacturers to label products that contain genetically modified organisms.

U.S. Reps. Chellie Pingree, D-1st District, and Bruce Poliquin, R-2nd District, both voted against the bill, which passed in the House Thursday and would stymie Maine’s nascent GMO labeling law.

The bill would block any mandatory labeling of foods that contain genetically modified ingredients, pre-empting state laws in Maine, Vermont and Connecticut, and undercutting efforts to pass similar labeling laws in other states.

Dubbed the Safe and Accurate Food Labeling Act by supporters, but the “Deny Americans the Right to Know” or DARK Act, by opponents, the measure was approved 275-150 with 45 Democrats voting in favor. There is not yet a companion bill in the U.S. Senate, but proponents say efforts to introduce one are picking up steam.

In interviews Friday, Pingree and Poliquin both said they’d continue to fight the bill.

Pingree said the fact that she and Poliquin opposed the bill together was “a reflection of how strongly people in Maine feel about this issue” of knowing the makeup of their foods.

“I don’t know if I got any mail to speak of in support of the bill. This is just one of those Maine issues,” she said. “People like to know what’s in their food, they like to buy it from farmers. It’s a growing interest in our state.”

House passage of the measure marks a victory for food and agricultural companies that have lobbied against labeling requirements, and a blow to consumers, health and environmental groups and organic food industry players who say food companies should disclose the presence of GMOs.

The Grocery Manufacturers Association, which represents more than 300 food companies, has been a key architect of the bill, aiming to squelch state efforts to force labeling of GMO foods.

Maine’s GMO labeling law, like Connecticut’s, requires neighboring states to pass similar initiatives before it goes into effect. Many of the New England states are considering such legislation, but the bill in Congress would quash those efforts.

Pingree said if the bill is introduced and passed in the Senate, she’d push President Barack Obama to oppose it.

“We will put a lot of effort into convincing the president to veto it,” she said. “It’s not just about labeling. There’s also the issue of state’s rights, and pre-empting those rights.”

Poliquin said he voted against the bill because of his desire to know what was in the food he fed his son, Sam, back when he was just a boy.

“I did all the cooking, shopping and what have you. I needed to be able to know what was in his belly,” Poliquin said. “I have no problem consuming GMO foods, but I think it’s really important that moms and dads know what they’re buying, and what they’re cooking.”

Opponents of mandatory GMO labeling say it unnecessarily demonizes food companies that use genetically modified ingredients by insinuating those ingredients are unsafe. But Pingree, an organic farmer herself, said the goal is to keep consumers informed, not scare them.

“I’m not trying to debate whether GMOs are good or bad for you. But why wouldn’t we let people know? If the orange juice is made from concentrate, it has to say so. We make a big deal about whether fish is farm-raised or wild-caught,” she said. “We label all this other stuff, but we’ve turned this into something that has to be kept secret.”

In addition to blocking mandatory labeling, the bill would allow food products that contain GMOs to be labeled by their producers as “natural.” The legislation would also nix laws that have been passed in some states to require buffer zones between organic and genetically modified crops.

Reuters contributed to this report. Follow Mario Moretto on Twitter at @riocarmine.