NICS is the FBI system that conducts background check on firearm buyers. Person received a denial (which means that the record shows the person in question doesn't qualify to purchase a firearm) is given the chance to appeal the result to FBI. Since October 2015, the appeal processing personnels have been reassigned to handle incoming checks, halting the entire appeal processing. At the time of the halting, the backlog dates back as early as June.
The halt essentially voided the due process of those denied purchase by the bureau. Thus we the people believe the status quo is unconstitutional. Since the FBI is under the jurisdiction of the Department of Justice, which in turn under that of the executive office, we the people also believe the White House is responsible to right the wrong.