breaking news in our national lead. the justice department is set to file a lawsuit to block at&t's takeover of time warner, a source tells cnn. time warner, the parent company of cnn. cnn's brian stelter is in new york. brian, i know you've been reporting this out. tell me what you've been learning. >> a year ago, this was a very, very unexpected. normally these deals get announced, it takes about a year for the approval process, the government gives its blessing usually with conditions and then you see deals become official. that's what was about to happen between at&t and time warner. they were weeks away from completing this mega media merger, but the government later today will file suit in order to block the deal. that means a lengthy court process may be ahead. this is something that has been the talk of the antitrust community because there are two theories here, jim, on what's going on. the first is that the trump administration has legitimate and real concerns about whether this deal is anti-competitive, whether it would harm consumers.