WASHINGTON — The Trump administration determined that more than 500,000 children would no longer be automatically eligible for free school meals under a proposed overhaul to the food stamp program, but left that figure out of its formal proposal, according to House Democrats.

The Department of Agriculture wants to crack down on eligibility for food stamps, estimating that 3.1 million Americans would lose benefits under the proposed rule that the agency unveiled on Tuesday.

The proposal, however, did not include the USDA’s own estimate that more than 500,000 children would lose automatic eligibility for free school meals under the proposed change, according to Rep. Bobby Scott, D-Va., chair of the House Committee on Education and Labor.

Under current law, children whose families receive food stamps are automatically enrolled in a federal program that offers free breakfast and lunch at school. The two benefit programs are linked to reduce paperwork and help ensure that children receive all of the food assistance they qualify for.

The agency declined to respond to questions about the rule’s impact, saying that it “cannot provide additional information during the public comment period,” a USDA spokesperson told NBC News.

USDA officials explained the impact on free school meals during a phone call with Scott’s staff on Monday, but did not mention the issue or its analysis of that effect in the formal rule published the next day, Scott said in a letter sent Friday to Agriculture Secretary Sonny Perdue.

During the call, the USDA said that 93 percent of the children affected by the change — more than 465,000 total — would qualify for reduced-priced meals, according to Scott’s staff. Under that program, schools can charge up to 30 cents for each breakfast and 40 cents for each lunch.

But families would need to apply individually for assistance, creating paperwork requirements that could lead some qualified children to fall through the cracks, and some families still may not be able to afford the meals, even at a significantly reduced cost, anti-poverty advocates say. Some children may continue to receive free school meals through other programs.

Scott believes that the USDA’s omission violates federal requirements that all proposed rules include “relevant scientific and technical findings.”

In his letter, Scott requests that the USDA immediately revise its proposed rule to include its impact on the school meal program, as well as provide an explanation for the failure to include these findings in its original proposal. The public has 60 days to comment on proposed rules after they are published in the Federal Register.

The Trump administration wants to undo rules that allow states to raise food stamp eligibility requirements, which make it easier for families with high housing and child care costs, as well as those with savings and other assets, to receive the assistance.

“Too often, states have misused this flexibility without restraint,” Perdue said in a statement on Tuesday. “That is why we are changing the rules, preventing abuse of a critical safety net system, so those who need food assistance the most are the only ones who receive it.”

Anti-poverty advocates say they believe the changes will harm families struggling to make ends meet, explaining that free school meals are vital to addressing hunger.

“Food is the easiest thing to cut out of a household budget,” says Lisa Davis, senior vice president of the No Kid Hungry campaign at Share Our Strength, an advocacy group. “The parents start missing meals to avoid that impact on the kids. And the older kids — the ones in middle school and high school — they often will skip meals to make sure there’s food for the little ones.”