Robert Mueller Is Testifying Tomorrow. Here’s What You Need to Know.

WASHINGTON — After two years of silence and one brief public statement, the special counsel, Robert S. Mueller III, will finally sit for prolonged questioning at two House hearings on Wednesday. Though he has expressed reluctance about testifying and has vowed to discuss only the contents of his 448-page investigation report, his appearances are nonetheless highly anticipated. Members of Congress will be trying to find ways to highlight the report’s findings or undermine them.

When: The House Judiciary Committee hearing starts at 8:30 a.m. Eastern on Wednesday and is expected to last about three hours, followed by a short break and the House Intelligence Committee hearing at noon for about two hours.

Where: Capitol Hill

Who: The Democratic chairmen of the two committees, Representatives Jerrold Nadler of New York and Adam B. Schiff of California, will set the tone and lead the questioning for both sessions. But Republicans are preparing to try to counter them, led by Representatives Doug Collins of Georgia and Devin Nunes of California, with an assist from Representative Jim Jordan of Ohio, one of the most vocal critics of the Russia investigation.

How to watch: The New York Times will stream Mr. Mueller’s testimony, and our reporters will provide live context and analysis.

  • Obstruction. Much of the discussion at the first hearing, in the Judiciary Committee, is expected to revolve around the second volume of Mr. Mueller’s report, an exhaustive account of the president’s attempts to impede investigators. Mr. Mueller and his team did not decide whether Mr. Trump’s efforts amounted to criminal obstruction of justice but also declined to exonerate him.

  • Collusion. The Intelligence Committee will focus on the first volume of the report, which described Russia’s 2016 election interference. Investigators found repeated contacts between Russian intermediaries and the Trump campaign, whose advisers welcomed the help and expected to benefit from it, but not sufficient evidence to prove a conspiracy.

  • Mr. Mueller is expected to hew closely to his report, though lawmakers do not intend to make his testimony that easy for him. In May, during his only public appearance as special counsel, Mr. Mueller framed that document as his testimony to Congress and said he hoped that he would not have to testify.

  • The Democrats want Mr. Mueller to bring to life the most serious acts of possible obstruction in the report. They believe that many Americans lack a full understanding of Mr. Trump’s efforts to impede the inquiry and that Mr. Mueller’s recounting of it will leave an impression on voters. They may also try to push the taciturn Mr. Mueller to more clearly state whether Mr. Trump could have been charged with obstruction if not for Justice Department guidelines that say a sitting president cannot be prosecuted.

  • The Republicans want to focus on parts of the report they view as beneficial to the president: namely Mr. Mueller’s decision not to charge anyone with conspiracy. But they have a litany of other questions about the investigation itself, beginning with its length. Republicans disagree about how hard to go after Mr. Mueller, but intend to ask about potential anti-Trump bias in the F.B.I. and among prosecutors on his team, many of whom have worked for or donated to Democratic causes, and some of the questions could get combative.

Their chief accomplishment would be getting Mr. Mueller to say that the president would have been charged with a crime if not for the Justice Department guidelines. But they also hope that he gives tacit or explicit endorsement of an impeachment investigation by Congress. Both are unlikely. More realistically, Democrats want average Americans watching at home to come away outraged by the president’s behavior.

The status quo. Republicans believe that if Mr. Mueller simply reiterates his report and keeps from helping Democrats, they have succeeded. They also hope to sow doubt about the fairness of Mr. Mueller’s investigation itself.

Be boring, very boring. Mr. Mueller wants to avoid entanglement in the political fray and leave with his reputation for independence unblemished.