Former special counsel Robert Mueller is giving lawmakers their first opportunity to question him about his report on Russian interference in the 2016 election and President Trump's efforts to curtail that investigation.

In his opening statement to the House Judiciary Committee, Mueller said his testimony will be "limited," and reiterated that he planned to stay within the bounds of the 448-page report he submitted in March.

"I do not intend to summarize or describe the results of our work in a different way in the course of my testimony today," Mueller said. "As I said on May 29: the report is my testimony. And I will stay within that text."

Mueller also emphasized the severity of Russia's efforts to interfere in the 2016 campaign.

"Over the course of my career, I've seen a number of challenges to our democracy," he said. "The Russian government's effort to interfere in our election is among the most serious. As I said on May 29, this deserves the attention of every American."

Mueller's testimony before the Judiciary Committee began at 8:30 a.m., and he will testify before the House Intelligence Committee for two hours.

During his nearly two-year investigation, Mueller found that Russia meddled in the 2016 campaign through an operation to break into computer networks and sow division on social media to bolster Mr. Trump at the expense of Hillary Clinton. He did not, however, establish that Trump campaign officials "conspired or coordinated with the Russian government in its election interference activities."

The special counsel also declined to make a determination about whether Mr. Trump obstructed justice, although his report outlined 10 instances of potential obstruction. After Mueller submitted his report in March, the attorney general determined there was insufficient evidence to conclude Mr. Trump had obstructed justice.

Mueller says report did not “totally exonerate” the president

8:54 a.m.: Questioning Mueller first, Nadler asked whether the report totally exonerated the president, as Mr. Trump and his allies have frequently claimed.

"No," Mueller responded.

Mueller also reiterated his report did not clear the president of obstruction of justice, and that while a sitting president could not be indicted under Department of Justice guidelines, he could be indicted after leaving office.

-- Grace Segers

Mueller says his testimony will be "limited"

Mueller is sworn in before he testifies before the House Judiciary Committee hearing on his report on Russian election interference, on Capitol Hill on July 24, 2019. (Credit: Andrew Harnik / Associated Press)

 8:47 a.m.: In his opening statement, Mueller defended the independence of his investigation, saying he and his investigators aimed to "to work quietly, thoroughly, and with integrity so that the public would have full confidence in the outcome."

Mueller added that his testimony would be "limited" due to ongoing litigation, and because he was unable to comment on the origins of the investigation and the so-called "Steele dossier" -- a key talking point for Republicans on the committee.

"These matters are the subject of ongoing review by the Department. Any questions on these topics should therefore be directed to the FBI or the Justice Department," Mueller said about the origins of the investigation.

He also indicated his testimony Wednesday would not include any new information.

"I do not intend to summarize or describe the results of our work in a different way in the course of my testimony today. As I said on May 29: the report is my testimony. And I will stay within that text," Mueller said, adding that he would not comment on Barr's determination that Mr. Trump did not obstruct justice.

"Over the course of my career, I've seen a number of challenges to our democracy. The Russian government's effort to interfere in our election is among the most serious. As I said on May 29, this deserves the attention of every American," Mueller concluded.

-- Grace Segers

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