(WASHINGTON) — The first volleys between the National Football League and a congressional committee seeking to investigate the Washington Football Team emails that got Las Vegas Raiders coach Jon Gruden fired—as well as other related documents—show that the congressional probe is likely to be a drawn-out affair.

The House Oversight and Reform Committee indicated last month that it intends to mount an investigation of the leaked emails that were part of an NFL probe into the Washington Football team. The emails showed Gruden making racist and anti gay comments and resulted in his resignation.

The committee on Friday called on the NFL to lift restrictions on people who might have information in the league’s investigation of the workplace culture at the team owned by Dan Snyder. The league, meanwhile, said it had responded to the committee’s initial inquiry, and that it intended to cooperate.

The back-and-forth came a day after a deadline the committee had given the league to respond to its demand for documents related to the league. It marks the beginning of what effectively amounts to a negotiation over which documents the league will turn over.