During a break that he requested, Mr. Lewandowski shared on Twitter a link to a website for a new super PAC that was created Tuesday, Stand With Corey.
Mr. Trump, who watched the proceedings from Air Force One, cheered on Mr. Lewandowski. “Such a beautiful Opening Statement,” he tweeted. “Thank you Corey.”
Republicans derided Democrats’ investigation as a stunt.
“The majority made a promise: We’ll impeach him. We’ll investigate him. For most of them, it happened in November 2016 because they couldn’t believe Donald Trump won,” said Representative Doug Collins of Georgia, the top Republican on the panel. “And they still can’t get over it today. So what do we do? We have public hearings, lots of flashbulbs, embarrassing the president — not doing an investigation, not doing oversight.”
Democrats intend to stay the course, though divisions persist in their caucus over impeachment.
The Judiciary Committee is sitting on unused subpoenas that it could deploy in the coming weeks to compel testimony from a handful of the most prominent Trump administration figures connected to Mr. Mueller’s report, including John F. Kelly, the former White House chief of staff; Jared Kushner, Mr. Trump’s son-in-law and senior adviser; Mr. Sessions; and Rod J. Rosenstein, the former deputy attorney general who appointed Mr. Mueller and oversaw his work.
Democrats will also try to broaden their inquiry to other accusations of corruption and malfeasance. On Tuesday, they announced a hearing for next week focused on whether Mr. Trump’s businesses have illegally profited from spending by foreign and domestic government spending in violation of the Constitution’s emoluments clauses.
The committee had also set a deadline Tuesday for homeland security officials to produce any relevant documents related to reported meetings in which Mr. Trump dangled pardons for any officials fearful that they might break the law by enforcing his policies at the border. It was not immediately clear whether the administration complied.
Maggie Haberman, Catie Edmondson and Mark Mazzetti contributed reporting.