Former special counsel Robert Mueller is testifying Wednesday before two House committees, where he will answer questions for the first time about his nearly two-year investigation of Russian election interference in the 2016 presidential election.
Here's what you need to know about the hearings:
When does it start?
Mueller's first hearing before the Judiciary Committee is set to begin at 8:30 a.m. ET. He is expected to testify before the 41-member committee for about three hours.
After a short break, he will appear before the 22-member Intelligence Committee around noon and testify for about two hours.
What has Mueller already said?
Not much. He gave brief public remarks at a news conference in May, when he announced that he would step down as special counsel. He took no questions, and told reporters, "Any testimony from this office would not go beyond our report."
The Justice Department also reportedly told Mueller to limit his testimony to the findings in his report.
He is expected to give an opening statement Wednesday. Mueller will be accompanied by Aaron Zebley, his former deputy special counsel, to the hearings, Mueller's spokesman told NBC News.
What will Democrats ask?
Some Democrats, including Intelligence Committee Chairman Adam Schiff of California and Judiciary Chairman Jerry Nadler of New York, have said they want Mueller to share the findings of his report with the American public, most of whom have probably not read his 448-page findings. But they have also said their questions go beyond the report.
Democrats plan to split their line of questioning between the two committees, congressional aides told reporters last week. The Judiciary Committee will focus on the volume of the report that dealt with obstruction, while the Intelligence Committee will ask Mueller about Russia's attempts to interfere in the presidential election, the aides reportedly said.
What will Republicans ask?
Republicans on the committees have signaled they plan to press Mueller to respond to allegations of anti-Trump political bias on his investigative team.
Some members, such as Judiciary's ranking Republican, Rep. Jim Jordan, R-Ohio, are poised to ask about a salacious and unverified dossier that was used to obtain a search warrant for a former Trump campaign aide, as well as probe Mueller's knowledge of when he "knew" there was "no collusion" between Trump's campaign and the Kremlin.
What has Trump said?
Trump has railed against Mueller's probe as a "witch hunt" for nearly the entire time it was active. He slammed the hearings Monday, saying on Twitter that Mueller "should not be given another bite at the apple."
He said later that day that he might watch a "little bit" of Mueller's testimony.