The story behind the school lunch debate

WASHINGTON—First lady Michelle Obama and school lunch ladies used to be on the same team, but now they’re locked in a political war against each other.

For the first three years of Obama’s Let’s Move! campaign, the School Nutrition Association, a powerful group that represents 55,000 cafeteria professionals, was a close ally in the White House push to get kids to eat healthier.

The group helped lobby for the legislation at the center of the debate: the 2010 Healthy Hunger-Free Kids Act, a law championed by the first lady that mandates more fruits and vegetables, whole grains and less sodium in exchange for more federal funding on meals.