The fourth — and possibly final — congressional hearing on the Comcast-NBC Universal matchup takes place Thursday before the Senate Commerce Committee, but unlike the theater of the previous encounters, this one includes two key figures in deciding the fate of the pact.

FCC chairman Julius Genachowski and Christine Varney, in charge of the Department of Justice’s Antitrust Division, will testify in the first part of the hearing. The FCC and DOJ must sign off on the deal for it to go forward.

In the second group of witnesses, Comcast’s Brian Roberts will be joined by John Wells, president of the Writers Guild of America, West; Mark Cooper of the Consumer Federation of America; Colleen Abdoulah, president of WOW! Internet Cable and Phone; and University of Pennsylvania law professor Christopher S. Yoo.