Former Special Counsel Robert Mueller on Wednesday said in dramatic U.S. congressional testimony he had not exonerated President Donald Trump of obstruction of justice and defended the integrity of his inquiry under repeated attacks by conservative Republican allies of the president.

Mueller initially testified he would have sought to indict Trump were it not for a Justice Department policy against charging a sitting president. But hours later he corrected himself and said “we did not reach a determination as to whether the president committed a crime.”

Answering questions publicly for the first time on his inquiry, Mueller appeared for eagerly anticipated testimony in two back-to-back televised congressional hearings that carried high stakes for Trump and Democrats who are split between impeaching him or moving on to the 2020 election.

The former FBI director, who spent 22 months investigating what he concluded was Russian interference in a “sweeping and systematic fashion” in the 2016 U.S. election to help Trump and the president’s conduct, appeared for more than 3-1/2 hours before the House of Representatives Judiciary Committee.

Mueller then appeared before the House Intelligence Committee for more questioning. Democrats control the House, while Trump’s fellow Republicans control the Senate.

The Judiciary Committee’s Democratic chairman, Jerrold Nadler, praised Mueller and said no one, including Trump, is “above the law.” The Intelligence Committee’s Democratic chairman, Adam Schiff, accused Trump’s 2016 campaign of “disloyalty to country” for inviting, encouraging and making full use of Russian election meddling.

Mueller’s 448-page report, released in redacted form on April 18, did not reach a conclusion on whether Trump committed the crime of obstruction of justice in a series of actions aimed at impeding the inquiry, but did not exonerate him.

Republican Representative Steve Chabot said Wednesday’s hearing was the “last, best hope” by Democrats “to build up some sort of groundswell across America to impeach President Trump. That’s what this is really all about today.” Chabot also told Mueller some people thought his report was “a pretty one-sided attack on the president.”

Mueller’s investigation led to criminal charges against 34 people and three Russian entities. People who were convicted at trial or pleaded guilty included Trump’s former campaign chairman, deputy chairman and other aides.

He is scheduled to testify later before the House intelligence panel.