WASHINGTON (AP) — First ladies typically avoid getting into public scraps, but Michelle Obama has jumped into perhaps her biggest battle yet.

She’s fighting a House Republican effort to soften a central part of her prized anti-childhood obesity campaign and says she’s ready “to fight until the bitter end.”

Mrs. Obama even mocked the GOP effort in an opinion column and argued her case on Twitter.

“Remember a few years ago when Congress declared that the sauce on a slice of pizza should count as a vegetable in school lunches?” she wrote in The New York Times. “You don’t have to be a nutritionist to know that this doesn’t make much sense. Yet we’re seeing the same thing happening again with these new efforts to lower nutrition standards in our schools.”

Mrs. Obama lobbied largely behind the scenes four years ago for the Healthy Hunger-Free Kids Act of 2010, which requires more fruit, vegetables and whole grains in school meals, along with less sodium, sugar and fat. 

The School Nutrition Association, an industry-backed group that represents school cafeteria workers and originally supported the standards, has now turned against them. The association says it fully supports getting kids to eat healthier but says many districts are losing money because students aren’t buying the healthier lunches.

More than 1 million fewer students eat lunch at school each day since the first round of standards went into effect in 2012, following decades of steadily increasing participation.