Former Trump campaign manager Corey Lewandowski refused to answer questions from the House Judiciary Committee that involved conversations with President Trump not referenced in the Mueller report, dealing a blow to Democrats hoping for new revelations in what the committee has labeled its first "impeachment hearing."Highlights: Lewandowski began the hearing by telling Chairman Jerry Nadler (D-N.Y.) that the White House has instructed him not to provide answers that could not be found in the Mueller report. The hearing was then delayed for several minutes because Lewandowski did not have a copy of the report in front of him.A frustrated Nadler accused Lewandowski of "filibustering" and asked for the 5-minute clock governing his question time to be paused. This prompted outcry from Ranking Member Doug Collins (R-Ga.) and caused the hearing to quickly devolve into an argument over parliamentary procedure.Rep. Steve Cohen (D-Tenn.) later inquired about Trump asking Lewandowski to direct then-Attorney General Jeff Sessions to limit the scope of the Mueller investigation — the episode that is at the crux of Lewandowski's importance as a witness to potential obstruction of justice. Lewandowski responded: "The president never asked me to do anything illegal."Under questioning from Rep. Hank Johnson (D-Ga.), however, Lewandowski confirmed that the Mueller report accurately describes his conversations with Trump about getting Jeff Sessions to unrecuse himself and limit the scope of the Russia investigation. Throughout the hearing, Lewandowski confirmed that the Mueller report was accurate as far as his role was concerned.In a combative exchange with Rep. Eric Swalwell (D-Calif.) — whom Lewandowski mockingly called President Swalwell in reference to his failed presidential bid — Lewandowski refused to read aloud from the Mueller report. Rep. David Cicilline (D-R.I.) subsequently demanded that Lewandowski be held in contempt.Under grilling from committee counsel Barry Berke, Lewandowski would not answer whether he lied in an interview on MSNBC about speaking to Jeff Sessions: "I have no obligation to be honest with the media because they are just as dishonest as everybody else." Lewandowski later told Berke, "Never have I called into question the validity of the Mueller report," though he said in his opening statement that the investigation was an attempt to "take down a duly elected President of the United States." Lewandowski would also not answer whether Mueller offered him immunity in exchange for answering questions.The big picture: Lewandowski is the first Mueller witness to be publicly interviewed in the months since the conclusion of the special counsel's investigation. The others — including former aides Don McGahn, Hope Hicks, Rick Dearborn and Rob Porter — have been blocked from testifying by the White House, which has invoked claims of "absolute immunity" that are currently being challenged by Democrats in court.Between the lines: As Axios' Alayna Treene reported last week, Lewandowski was expected to put on a combative performance at the hearing in anticipation of a potential run for Senate in New Hampshire."Corey will use [the hearing] as part of the campaign," Thomas Rath, former attorney general of New Hampshire, told Axios. "He will be confrontational to the Democrats. He will be totally loyal to Trump. And he will be playing to the right wing of the party who need to unite behind him in a primary."Trump himself tweeted shortly after the hearing began: "Such a beautiful Opening Statement by Corey Lewandowski! Thank you Corey!"This story is developing. Please check back for updates.