Hillary Clinton became the latest to denounce Barr’s testimony on the handling of the Mueller report amid calls for his resignation

The powerful House of Representatives judiciary committee will be faced with an empty chair on Thursday morning after the US attorney general, William Barr, rebuffed a call to testify about his approach to the report of the Trump-Russia investigation by special counsel Robert Mueller.

The refusal escalates a running battle with congressional Democrats over his handling of the Mueller report amid rising calls for his resignation.

A ‘snitty’ day: five takeaways from attorney general's testimony Read more

The hearing is set to go ahead at 9am, although it is unclear what the Democrat-led committee will achieve without its star witness, one day after an explosive hearing on Capitol Hill when Barr appeared before the Republican-led Senate judiciary committee.

The justice department said that Barr was withdrawing his participation in protest of the decision of the committee’s Democratic chairman, Jerry Nadler, to allow a staff counsel to question him alongside members. But the move is likely to expose Barr to accusations that he is trying to avoid accountability over his role in the release of the Mueller report into Russian interference in the 2016 presidential election.

Attention is now focused on when, indeed whether, Mueller himself will come before the House to testify.

On Wednesday night, Nadler said he would not subpoena Barr to appear on Thursday.

But, in a statement, Nadler added: “Given his lack of candor in describing the work of the special counsel, our members were right to insist that staff counsel be permitted to question the attorney general. I understand why he wants to avoid that kind of scrutiny, but when push comes to shove, the administration may not dictate the terms of a hearing in our hearing room.”

A four-page summary of the Mueller report that the attorney general handed to Congress on 24 April has come under fire for putting a sheen over the report favorable to Donald Trump.

On Wednesday night, Hillary Clinton waded into the fray with an excoriating denunciation of the attorney general. She told MSNBC that his testimony before the Senate judiciary committee earlier in the day had been “incredibly arrogant” in its “level of disregard, even contempt for Congress”.

The positions Barr took, Clinton said, were unlike anything she had ever heard before. They went “to the core of whether we are a nation of laws or a nation of strongmen”.

Clinton, who was Trump’s rival in the 2016 election and the subject of much of the Russian interference that prompted the Mueller investigation, went on to accuse Barr of acting like “the president’s defense lawyer – he is not the attorney general of the United States in the way he has conducted himself”.

Clinton’s intervention came shortly after Barr faced hours of piercing questioning from Democrats on the Senate judiciary committee, in the course of which he was repeatedly accused of lying to or misleading the American people. By the end of the day, numerous Democrats, including the presidential candidates Cory Booker, Kirsten Gillibrand, Kamala Harris and Elizabeth Warren, had demanded his resignation.

Barr stands accused of spinning the 448-page report to make it look as though Mueller definitively concluded that there was no collusion or cooperation between Trump and his campaign and the Russian government. In fact, the Mueller report is packed with details of links between Trump associates and the Russian government as well as at least 11 attempts by the president to impede the special counsel’s investigation – a potentially criminal action upon which Mueller reached no conclusion, indicating that he was leaving it for Congress to decide.

On Wednesday, the justice department released the full text of a letter in which Mueller complained to Barr directly that his summary of the report had given a partial account of the investigation. “Public confusion” had arisen as a result.

Barr further compounded the rift with Democrats in the way he spun Mueller’s letter. In the attorney general’s account of events, he spoke with the special counsel the day after he received the letter and, in the course of a 15-minute conversation, Mueller assured him he did not think his summary had been at all inaccurate.

That conflicts with the spirit of the Mueller letter, which was deeply critical of Barr’s summary, lamenting that it “did not fully capture the context, nature, and substance of this office’s work and conclusions”.

Democratic anger over the attorney general’s conduct has been further aggravated by his failure to meet a Wednesday deadline for him to turn over the full unredacted version of the Mueller report to the House judiciary committee. Nadler told reporters that if there was no compliance with the subpoena within a couple of days, he would begin contempt of Congress proceedings against Barr.

On the Republican side of the aisle, party leaders are scrambling to try to bring the investigation into potential obstruction of justice to a halt. At the end of the Senate hearing on Wednesday, Lindsey Graham, the Republican chairman of the judiciary committee, said: “I’m not going to do any more. Enough already. It’s over.”

As part of that shutdown, he said he would not be calling Mueller himself to testify. But with Democrats in charge of the House, and the packed field of Democratic candidates for next year’s presidential election stepping up their calls for Barr to resign, the fight appears to be only just beginning.