Attorney General William P. Barr testifies before the Senate Judiciary Committee on Capitol Hill, May 1. (J. Scott Applewhite/AP)

House Democrats on Monday moved closer to holding Attorney General William P. Barr in contempt of Congress, agreeing to vote on the question this week, a rare rebuke for the nation’s top law enforcement official in the intensifying fight between the Trump administration and Congress.

A second possible confrontation also looms as Democrats discuss a possible contempt citation for Donald McGahn, President Trump’s onetime lawyer, according to multiple Democratic officials. 

The former White House counsel — a major figure in special counsel Robert S. Mueller III’s investigation into whether Trump obstructed justice — faces a Tuesday deadline to turn over 36 types of documents subpoenaed by the House Judiciary Committee, most relating to Mueller’s nearly two-year probe of Russian interference in the 2016 election.

But White House officials have signaled that they may claim executive privilege and try to bar McGahn from complying, raising the possibility of a contempt citation for McGahn should he go along with that plan.

A House Democratic official, speaking on the condition of anonymity to discuss private deliberations, said talks between McGahn and the Judiciary panel are ongoing, and investigators remain hopeful that he will comply. The committee also is seeking his testimony. But if he doesn’t cooperate, contempt is one option, the individual said: “Democrats will consider all options if necessary.”

“McGahn has every right to testify. . . . He has a responsibility to testify,” said House Judiciary Committee member Jamie B. Raskin (D-Md.), who did not know what the panel would do if McGahn refused. “Any relevant executive privilege [claim] was waived long ago when McGahn went and spent more than 30 hours being interviewed by the special counsel, so it’s very hard to imagine that you can put the toothpaste back in the tube.”

The ongoing conflict between the two branches of government occurs as Trump has repeatedly insisted the Mueller report has exonerated him and has vowed to fight all subpoenas from congressional investigations. (Barr has released a redacted version of Mueller’s report but not the full report.)

Democrats have decried Trump’s resistance as stonewalling, maintaining that the president is thwarting Congress’s ability to conduct oversight.

Trump tweeted Monday that he did nothing wrong — “No High Crimes & Misdemeanors,” No Collusion, No Conspiracy, No Obstruction. ALL THE CRIMES ARE ON THE OTHER SIDE.” His pronouncements stood in contrast to more than 450 former federal prosecutors who worked in Republican and Democratic administrations, who signed a statement asserting Mueller’s findings would have produced obstruction charges against Trump — if not for the office he held.

The statement offered a rebuttal to Barr’s determination that the evidence Mueller uncovered was “not sufficient” to establish that Trump committed a crime. “Each of us believes that the conduct of President Trump described in special counsel Robert S. Mueller III’s report would, in the case of any other person not covered by the Office of Legal Counsel policy against indicting a sitting president, result in multiple felony charges for obstruction of justice,” the former federal prosecutors wrote.

In the latest move by the administration to shield the president from congressional inquiries, Treasury Secretary Steven Mnuchin told House Democrats on Monday he would not furnish Trump’s tax returns despite their legal request.

Mnuchin, in a letter to House Ways and Means Committee Chairman Richard E. Neal (D-Mass.), said he had consulted with the Justice Department and that they had concluded that it would not be lawful for the administration to turn over the tax returns because of potential violations of privacy.

Frustrated with the no-cooperation strategy of the administration, the Judiciary Committee is scheduled to vote Wednesday on whether to hold Barr in contempt for failing to comply with a congressional subpoena and produce the full, unredacted version of the Mueller report.

Such a reproach would be only the second time in history that a sitting attorney general received that type of reprimand; the Republican-led House voted in 2012 to hold Attorney General Eric H. Holder Jr. in contempt over his unwillingness to fulfill their demands for material in the probe of Operation “Fast and Furious,” the federal government’s program to attack gun trafficking to Mexican cartels.

Judiciary Committee Chairman Jerrold Nadler (D-N.Y.) said his panel has “attempted to engage in accommodations with Attorney General Barr for several months, it can no longer afford to delay, and must resort to contempt proceedings.”

The contempt resolution that the panel will vote on says that without the full, unredacted Mueller report and underlying evidence, “the committee is unable to fully perform its responsibility to protect the impending 2020 elections — and thus our democracy itself — from a recurrence of Russian interference.”

Democrats also said they needed the report as they decide “whether to approve articles of impeachment with respect to the president or any other administration official, as well as the consideration of other steps such as censure or issuing criminal, civil or administrative referrals.”

Justice Department spokeswoman Kerri Kupec said Monday that the attorney general “has taken extraordinary steps to accommodate the House Judiciary Committee’s requests for information regarding the special counsel’s investigation” and invited committee staff to the department Tuesday. A contempt citation against Barr would set up a lengthy legal battle over the Mueller report, as Democrats take the matter to civil court.

The next front in the fight is McGahn’s documents and testimony. McGahn emerged in the Mueller report as a senior confidante who documented in real-time Trump’s rage against the Russia investigation and efforts to shut it down. 

The special counsel has identified two episodes in which McGahn was a critical witness and in which investigators say they have substantial evidence Trump was engaged in obstruction of justice that would normally warrant criminal charges. In mid-June 2017, Trump tried to pressure McGahn to intervene with the Justice Department to try to push for Mueller’s removal from office based on alleged conflicts of interest, the report said. In February 2018, Trump summoned McGahn to the Oval Office and urged him to deny a news account that suggested the president asked for his help in ousting Mueller. 

House Democrats want to hear McGahn’s firsthand account — especially on the powerful medium of live television — and ask what he thought of Trump’s behavior. They gave him until Tuesday to turn over documents and until May 21 to testify. 

McGahn and his attorney, William Burck, are preparing for the likelihood that the White House will assert executive privilege to try to prevent him from testifying. But if the White House’s legal argument of privilege is questionable, McGahn puts himself at some risk by resisting Congress’s subpoena for his testimony.

Burck declined to comment Monday.

Traditionally, a senior adviser’s private communications with the president would be shielded by executive privilege to allow a president to seek the honest counsel of his aides without fear of their full-throated discussions being shared with the public while he is in office. However, in this case, McGahn’s private discussions with Trump during these two critical episodes are clearly documented in the Mueller report and available for the public to review in detail. 

Multiple former House counsels and congressional experts expressed skepticism about the merits of the White House trying to keep McGahn from testifying on anything related to Mueller’s probe.

“The key waiver was the attorney general’s release of the Mueller report, that made it public” said former House counsel Irvin B. Nathan, who worked under Rep. Nancy Pelosi (D-Calif.) during her first term as speaker. “There’s no justification for executive privilege any longer — and there’s not a chance that any court would say that executive privilege has not been waived.” 

Ultimately, the decision about what to do will be left to McGahn, House experts say, putting him in a position of having to choose between Trump and a possible contempt of Congress charge.

“He’s between a rock and a hard place,” said former House counsel Kerry W. Kircher, who worked for the last GOP majority and does not think a White House assertion of privilege will hold up in court. 

Kircher said contempt for McGahn, now in private practice, would be a major stain on his résumé: “For a lawyer in Washington to have been held in contempt, you would swallow long and hard before you do that. . . . He’s not an elderly guy on the verge of retirement. He has a lot of good years of his career left.” 

How McGahn and his lawyers decide the issue will probably have a domino effect on other aides whose testimony House Democrats are also seeking. If McGahn concludes he must testify, the president’s former chief of staff Reince Priebus and McGahn’s chief of staff Annie Donaldson, who kept detailed notes of the president’s conversations with McGahn, could follow his path to the witness chair. 

Both, notably, keep the same counsel.

Ellen Nakashima and Devlin Barrett contributed to this report.