The nation’s  school cafeteria food fight escalated Wednesday as lobbying groups, the Secretary of Agriculture and even a group of retired generals weighed in on whether the new federal school lunch program is working effectively --  or needs to be put on hold.

The House Appropriations Committee is expected to vote Thursday on legislation that would grant waivers to school districts that report they are having financial problems as they comply with the dietary requirements of the Healthy Hunger-free Kids Act, which passed in 2010.

First Lady Michelle Obama came out swinging against the waiver idea on Tuesday. In a rare display of public opposition to a legislative proposal, Mrs. Obama said that the plan, authored by congressional  Republicans,  “is unacceptable to me not just as first lady but also as a mother.”

Her views were backed late Tuesday by 19 past presidents of the most influential lobby on cafeteria policy, the School Nutrition Association (SNA). They jointly sent a letter to Senate and House Appropriators urging them to “reject calls for waivers” and “maintain strong standards in all schools.”

In a dizzying shift, that view was countered Wednesday when the current leadership of the SNA held a press conference call with several school nutrition directors from around the country who backed the waiver legislation.

“We can't force students to eat something they don't want,” said Lyman Graham, Food Service Director of a consolidated school district near Roswell, N.M., who reported his students won’t eat whole wheat tortillas. “With sky-high produce costs, we simply cannot afford to feed our trash cans.  Every penny spent on whole grains and produce needs to go into the mouth of a hungry child," he said.

The president of the 55,000 member SNA organization, Leah Schmidt, said  “the administration’s own data proves that student participation in school lunch is abruptly down in 48 states despite rising school enrollment and 30 years of steady program growth.”

She added:  “School meal programs need more flexibility,”

As if in answer to those concerns, the USDA Wednesday announced it will allow schools a two year delay from a requirement that all pasta served in schools be more than half whole grain. Schools will be granted the delay if they can demonstrate that they have had “significant challenges” in preparing whole grain pasta. Some of the nutritionists on the SNA called the decision a good first step, but said more flexibility was needed.

In his own press call Wednesday, Agriculture Secretary Tom Vilsack said his department was committed to flexibility and listening to schools while still moving the health nutrition program forward, an initiative he said was already showing results, according to scientific and school studies.

“Now is not the time for a politicians to substitute their judgement” over those of scientists, he said.

In the escalating barrage of press releases, a professor  from Mount Sinai Hospital endorsed that view, saying empirical evidence already shows that the school dietary guidelines are effective.

Dr. Christopher Ochner,  a professor at the Icahn School of Medicine at Mount Sinai said the rules were already having a "significant impact" on obesity.

“At a time when we are beginning to make strides in the fight against childhood and adolescent obesity, a measure to allow districts to opt out of The Healthy, Hunger-Free Kids Act of 2010 would be a significant set-back,” he said in a prepared statement.