Updated at 6:37 p.m. ET

Attorney General William Barr declined to appear before a hearing scheduled on Thursday before the House Judiciary Committee following hours of sometimes tough back-and-forth on Wednesday in the Senate.

The chairman of the House panel, Rep. Jerry Nadler, D-N.Y., said that Barr was risking a contempt of Congress citation and that he would go ahead with his planned hearing — with an empty witness chair if necessary.

The Justice Department, however, said Nadler was being unreasonable by asking for Barr to take questions not only from members of Congress, but also from lawyers on the professional staff of the committee.

Nadler also had wanted the possibility to go into closed session to discuss redacted aspects of the report filed by Justice Department special counsel Robert Mueller.

No, said a Justice Department spokeswoman. Barr would not play.

"Chairman Nadler placed conditions on the House Judiciary Committee hearing that are unprecedented and unnecessary," a statement said.

The statement continued:

Chairman Nadler's insistence on having staff question the attorney general, a Senate-confirmed Cabinet member, is inappropriate. Further, in light of the fact that the majority of the House Judiciary Committee – including chairman Nadler – are themselves attorneys, and the chairman has the ability and authority to fashion the hearing in a way that allows for efficient and thorough questioning by the members themselves, the chairman's request is also unnecessary.

The chairman scoffs

Nadler, citing how "dishonest" he said Barr has been, said he wasn't surprised the attorney general didn't want to subject himself to questioning by professional staffers without the five minutes-per-member rule that normally governs House hearings.

Nadler told reporters that witnesses may not dictate the terms under which they appear before congressional committees and that he hoped Barr would change his mind by the time Nadler brings down his gavel on Thursday morning.

The committee's top Republican, Rep. Doug Collins of Georgia, lamented what he called the lost opportunity his members would have to question Barr and what he called Democrats' attempt to stretch out the Russia affair in order to continue to try to score political points against President Trump.

"By rejecting the chance to question Attorney General Barr or read the materials he's provided, Democrats are trying to prolong an investigation the special counsel completed," Collins said. "Ultimately, though, they're ignoring the will of the majority of Americans who want Congress to move on and secure our border and continue to strengthen our economy."

Acrimony in the upper chamber

The byplay over the House hearing followed a long session on Wednesday in the Senate Judiciary Committee, where Barr testified for several hours.

Barr defended his handling of Mueller's investigation and Trump's actions surrounding it, which critics say amount to obstruction of justice.

Barr said Mueller "was allowed to complete his work as he saw fit" and said he was "frankly surprised" that Mueller did not reach a decision on whether Trump had obstructed justice.

Barr concluded that he had not.

One of the main threads of questioning by Democrats was over a letter released by the Justice Department on Wednesday from Mueller, in which the special counsel expressed concern over Barr's March 24 letter to Congress summarizing the findings of the special counsel investigation.

Mueller wrote on March 27 that Barr's statement "did not fully capture the context, nature and substance of this Office's work and conclusions." It continued, "There is now public confusion about critical aspects of the results of our investigation."

In his testimony, Barr called the letter "a bit snitty" and said it was probably written by a member of Mueller's staff.

Barr told senators that after receiving the letter, "I called Bob," referring to Mueller, and asked him what the issue was and whether the March 24 letter was inaccurate. "He said no, but the reporting had been inaccurate."

Barr said Mueller told him that he wanted the report's executive summaries released. Barr testified that he told Mueller: "I wasn't interested in putting out summaries and I wasn't going to put out the report piecemeal."

Barr said he released his four-page statement, which he denied was a summary of the investigation because "the body politic was in a high state of agitation."

Barr and Mueller ultimately agreed to release a full, but partially redacted, version of the report.

Barr was also asked about testimony before the House in April in which he said he was unaware of reported concerns of Mueller's team.

"The question was relating to unidentified members who were expressing frustration," Barr said. But Sen. Patrick Leahy, D-Vt., responded, "I think your answer was purposely misleading, and I think others do too."

Later in the hearing, Sen. Mazie Hirono, D-Hawaii, launched into a blistering attack on Barr. "You lied," Hirono charged. "Being attorney general is a sacred trust. You have betrayed that trust. America deserves better. You should resign."

Senate Judiciary Committee Chairman Lindsey Graham, R-S.C., opened the hearing Wednesday by reading emails between two FBI agents who were in charge of the investigation of former Secretary of State Hillary Clinton's email server and vowed the panel would "look long and hard at how this started."

As for the Mueller investigation, Graham said, "I have read much of the report," adding, "For me, it is over." He repeated that assertion after the hearing concluded and said he did not intend to invite Mueller to testify before the committee.

Democrats scoffed at Republican members of the panel who repeatedly returned to the investigation into Clinton's emails.

"My Republican colleagues are going to work to coordinate 'a lock-her-up defense,' " said Sen. Richard Durbin, D-Ill., who suggested questions also "have to be asked about Benghazi," along with "Travelgate and Whitewater," citing previous congressional investigations into former Secretary of State Hillary Clinton and President Bill Clinton. This "is totally unresponsive to what the American people want to know," Durbin said.

Addressing another point of criticism, Barr was asked to explain his conclusion that Trump had not committed obstruction of justice — given that the Mueller report explicitly "does not exonerate" Trump on the matter.

Sen. Dianne Feinstein, D-Calif., asked Barr whether former White House counsel Donald McGahn's testimony to Mueller's investigators that Trump told him to fire Mueller twice in the summer of 2017 didn't show that Trump was trying to obstruct the investigation. Barr replied with a vigorous defense of the president's actions.

"If the president is being falsely accused, which the evidence now suggests, that the accusations against him were false and he knew they were false and he felt this investigation was unfair, propelled by his political opponents and was hampering his ability to govern, that is not a corrupt motive" for replacing a special counsel, the attorney general said.

Later in the hearing, Barr said that two years of Trump's presidency "have been dominated by allegations that have now been proven false, and to listen to some of the rhetoric you would think the Mueller report had found the opposite."

Barr's defense of the president prompted Democrats on the panel to ask whether the attorney general would refrain from interfering in the 14 ongoing investigations that stemmed from the Mueller report.

Barr said he did not have any "substantive" discussions about those cases with anyone at the White House. He also said he would not recuse himself from overseeing those cases.

Sen. Kamala Harris of California, one of three Democratic presidential candidates on the committee, asked Barr whether anyone at the White House asked or suggested that he open an investigation into anyone. After a few moments of silence, Barr responded, "I'm trying to grapple with the word 'suggest.' "

Afterwards, Harris told reporters that she too thought Barr should resign.

White House press secretary Sarah Sanders tweeted a defense of Barr, saying, "Democrats only disgrace and humiliate themselves with their baseless attacks on such a fine public servant."

In a written statement to the Senate Judiciary Committee, Barr said he has kept the promises he made during his confirmation hearing to allow Mueller to finish his work without interference and share his report with Congress and the public.

The Justice Department released the report on Russian election interference on April 18 with redactions that Barr called "limited" and "necessary."

Nadler, D-N.Y., has issued a subpoena for Mueller's full report. He and other Democrats say they won't be satisfied until they hear from Mueller himself in open hearings about his investigation and the way it has been handled by the leadership of the Justice Department.

Nadler complained that even though Barr doesn't object to Mueller appearing, the Justice Department hasn't appeared keen to play ball.

"These reports make it that much more important for him to appear and answer our questions," Nadler said. "The Department of Justice has also been reluctant to confirm a date for special counsel Mueller to testify. Given this evening's reports, I will press the department to schedule that hearing without delay."

Democrats also focused on what they called the incompatibility between Barr's statement to Congress that he didn't know what Mueller thought about his handling of the special counsel's report and Mueller's letter faulting Barr's characterization of it.

Rep. Adam Schiff, D-Calif., the chairman of the House Intelligence Committee, and Rep. David Cicilline, a Rhode Island Democrat who sits on the Judiciary Committee, called on Barr to step down.

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