MONTPELIER (AP) - Vermont Gov. Peter Shumlin is set to sign a new law putting Vermont on track to be the first state to require labeling of genetically modified foods. But big obstacles remain for the law.

On one front, the food industry is widely expected to sue in a bid to overturn Vermont's law before it takes effect in mid-2016. The Grocery Manufacturers' Association hinted strongly at that possibility when the bill passed the Legislature two weeks ago.

On another front, Republicans in Congress are working on a bill that would forbid states from passing and enforcing laws like the one Shumlin is scheduled to sign on Thursday.

That, too, could derail an effort that backers say is aimed at letting consumers know how their food is made.