Senators have a history in demanding accountability from the NFL. When the Bidwill family was threatening to move the St. Louis Cardinals football team to Phoenix, for instance, Missouri Senators Jack Danforth and Thomas Eagleton pushed a bill to mandate league relocation procedures. The bill made it out of committee, but before it could get a vote on the floor, the NFL adopted its own set of relocation guidelines, using very similar language, McCaskill noted.

Her office is in the early stages of drafting legislation. Staffers said the goal is to make sure communities are treated fairly if a sports team that benefits from public funds — such as playing in a publicly financed stadium — decides to move to another community.

McCaskill said she’s not being vindictive. "I have a chance to make sure no other community will get treated like St. Louis," she said. "The heart of the NFL isn't just in the mega media markets."

Others are already examining more exactly how Kroenke won NFL approval to leave Missouri, she said. "There's a lot of things we have to take a look at," she said.

McCaskill hinted that regional leaders may be considering a suit against the NFL. If the NFL didn’t comply with its own relocation guidelines, her staff later clarified, it is possible anti-trust laws were violated.