The campaign of Sen. Bernie Sanders (I-VT) officially served the Democratic National Committee on Thursday with a lawsuit over the decision to suspend the campaign’s access to voter data after a staffer viewed confidential information back in December.

A source told The Hill the move was “very procedural” as Thursday was the deadline to file paperwork given to the campaign by a federal judge.

The DNC temporarily revoked the campaign’s access in mid-December to all voter information after a staffer inappropriately accessed voter data compiled by Hillary Clinton’s presidential campaign.

Sanders campaign manager Jeff Weaver said the DNC was holding the data “hostage.” Access was eventually restored and one Sanders staffer was fired.

The court filing on Thursday signaled the desire for an amicable resolution.

The filing from the Sanders campaign said both sides “continue to engage in cooperative discussions in their efforts to resolve the pending litigation,” according to New York magazine.