Agricultural interests, a big state retailers association, and an antipoverty activist are joining together to oppose an animal welfare ballot question that would mandate all eggs sold in Massachusetts be from cage-free hens.

On Wednesday, they created a ballot committee — Citizens Against Food Tax Injustice — to fight Question 3, which will appear on the November ballot. The move formalizes long-simmering opposition to the measure, which farm interests insist will sharply raise the price of food and disproportionately hurt poor people.

Proponents, including the Humane Society of the United States, paint the referendum question as a modest attempt to protect farm animals from inhumane treatment — to simply allow them to stand up, lie down, turn around, and extend their limbs.

Polls have found strong support among voters for the question, and backers have more than $1 million in the bank.

So how much will the new group be spending?

“Time will tell on that. More info to come,’’ said Diane Sullivan, the antipoverty advocate who will manage the campaign against Question 3.

But, she said, she’s keen to get the group’s message out.

“I want Massachusetts voters to understand what the unintended consequences of this question will be,’’ Sullivan said. “I want voters to know what the economic impact will be — higher food prices, which will particularly hurt low-income families.’’

Sullivan, who has six kids, was once homeless, and, until earlier this year, lobbied on behalf of homeless families on Beacon Hill, put it simply: “This is a regressive food tax.’’

But Stephanie Harris, a spokeswoman for Citizens for Farm Animal Protection, noted that most Massachusetts voters support her group’s effort. “Our 1,000 grass-roots volunteers are ready to work from now until Election Day to make sure this passes,’’ she said.

The new anti-Question 3 group is a coalition of the Massachusetts Farm Bureau, the National Association of Egg Farmers, the National Pork Producers Council, the New England Brown Egg Council, the Northeast Agribusiness and Feed Alliance, Protect the Harvest (a nonprofit with ties to the agriculture industry), and the Retailers Association of Massachusetts.

On Twitter, Jon Hurst, the president of the retailers association, said the measure is from the “do this, don’t do that crowd’’ and is likely unconstitutional. He called the question “regressive’’ and “anti-consumer.’’

The ballot question is backed by a coalition of groups including the Humane Society and the Massachusetts Society for the Prevention of Cruelty to Animals.

It would mandate that, starting in 2022, Massachusetts farms and businesses produce and sell only eggs from cage-free hens; pork from pigs not raised in or born of a sow raised in a small crate; and veal from calves not raised in a very tight enclosure.

There is debate over the cost consequences. Supporters say the price of a dozen eggs might go up 12 cents per dozen. Opponents say the cage-free mandate would mean cost increases of 80 cents or more per dozen.

Joshua Miller can be reached at joshua.miller@globe.com.