McCormick said: “Children need whole milk in their diet. But if children don't consume whole milk at school, they won't have an appetite or desire for whole milk later. This was a huge blow to dairy farmers here in Pennsylvania.”

It wasn't the first time McCormick talked about whole milk on the campaign trail. In fact, he has made this issue the focus of his campaign.

After attending Penn State University's AG Progress Days, Pennsylvania's largest outdoor agricultural show, back in August, McCormick told reporters that returning whole milk to schools was “a top priority for Pennsylvania,” adding the issue is “so obvious” and “the science is undeniable.”

Whole milk has not been served in schools since 2012. That's because of a 2010 law banning whole milk from the National School Lunch Program, which provides reduced-price or free lunches in nearly 100,000 schools. Former First Lady Michelle Obama championed the law in her “Let's Move!” program. Campaign to combat childhood obesity.

The 2010 edition of the “Dietary Guidelines for Americans” urged people to consume more dairy products, but recommended replacing whole milk and whole dairy products with fat-free or low-fat options to reduce solid fat intake.

However, new research suggests that whole milk may be healthier than low-fat milk.

Thiele says bringing whole milk back to school is good for children's nutrition and ensures dairy farmers remain “vibrant and successful.”

He believes current policies are having a slow impact on dairy farmers, who risk losing a generation or more of whole milk drinkers. From an economic perspective, whole milk is also better for Thiele. Dairy farmers like him are paid based on the butterfat content and protein content of their milk.

Sen. Bob Casey, who is running against McCormick, signed on in September to co-sponsor the Whole Milk for Heathy Kids Act of 2023. Pennsylvania's junior senator John Fetterman was an early co-sponsor and signed the bill back in June 2023.

Back in August, Casey told NBC News that he was wary of “the dietary guidelines for children” and that he wanted to ensure that any decision he made about whole milk was “based on science that is in the best interest of children.”

After meeting with farmers across Pennsylvania, he changed his mind about the bill. According to the Center for Dairy Excellence, there are about 5,000 dairy farmers in Pennsylvania.

Thiele says he's “glad” that Casey “finally” signed the Whole Milk for Healthy Kids Act of 2023, saying it's important that the bill has bipartisan support.

Currently, 11 Republican senators, five Democratic senators and one independent senator have signed on as co-sponsors of the bill.