What happens if a state law refuses to enforce a federal law?

I’ll give an example. The Federal Law that is probably going to be passed soon that requires restaurants to list calorie counts on their menus.

So let’s say that the law is passed. Well the thing is, when a business opens, it is the state, not the federal government, that issues the business license.

So suppose that if and when this federal law is passed requiring them to post calorie counts, a state just said, “Yeah, no, don’t worry about doing that, we won’t enforce it.”

What’s the federal government going to do?