Democrats in the US House of Representatives are about to vote on whether to hold Attorney General William Barr in contempt of Congress.
The judiciary committee took action after Mr Barr refused to submit an unredacted version of Special Counsel Robert Mueller’s report.
President Donald Trump has hit back by asserting executive privilege over the report, shielding it from public view.
The White House and Congress accused each other of abusing power.
Why is there a contempt vote?
The judiciary committee will vote on Wednesday on whether to recommend a contempt resolution against the attorney general for a full House vote.
Democratic lawmakers took action after Mr Barr did not comply with a legal order to release the Mueller report minus the redactions.
The redacted 448-page Mueller report, released last month, did not determine there was a criminal conspiracy between Moscow and the Trump campaign to influence the 2016 US presidential election.
But it detailed 10 instances where Mr Trump possibly attempted to impede the special counsel’s investigation.
Democrats say they need to see the full report and its underlying evidence to investigate possible obstruction of justice by Mr Trump.
House judiciary chairman Jerrold Nadler said the Trump administration’s refusal to provide the full Mueller report to Congress amounts to a “constitutional crisis”.
The New York Democrat said his party had “no choice” but to move forward with the contempt vote, “otherwise, we have a monarchy”.
But Doug Collins, a leading Republican on the committee, defended the Department of Justice’s decision to withhold of the Mueller material.
The Georgia lawmaker said Democrats were acting out of anger and fear “without any valid legislative reason”.
What does the contempt vote mean?
For Mr Barr to actually face the prospect of charges, the entire House, which Democrats control by 235 lawmakers to 197 Republicans, would have to vote against him.
The measure may be largely symbolic as it is seen as unlikely that the Department of Justice would actually indict its own head with criminal contempt.
However, it would send a powerful message to the White House about congressional Democrats’ refusal to submit in an increasingly bitter showdown.
Mr Barr would be the first attorney general held in contempt of Congress since the Obama administration’s Eric Holder in 2012.
How did the White House respond?
The White House accused Democrats of a “blatant abuse of power” and blocked access to the full Mueller report through a “protective assertion of executive privilege”.
Executive privilege allows a president to keep certain materials private if disclosing them would disrupt the confidentiality of the Oval Office decision-making process.
Press Secretary Sarah Sanders said that the president had rejected the Democratic committee chairman’s “unlawful and reckless demands” at the attorney general’s request.
She added in a statement: “They [Democrats] didn’t like the results of the [Mueller] report, and now they want a redo.”
The judiciary committee chairman argued the White House was misapplying the doctrine of executive privilege.
Mr Nadler said: “This decision represents a clear escalation in the Trump administration’s blanket defiance of Congress’s constitutionally mandated duties.”
Will Robert Mueller testify?
The House Judiciary Committee has formally requested that Mr Mueller testify, though a date has not been set.
The special counsel is still a Department of Justice employee, which means the attorney general could prevent him from testifying.
Mr Barr has previously said he would not mind Mr Mueller testifying before Congress.
Mr Trump, however, has called for the special counsel to not testify, tweeting: “No redos for the Dems!”
When Mr Mueller initially handed in his report, a spokesman said he would be leaving the department “within the coming days”.
If he does quit, he will become a private citizen and able to testify regardless of the department’s wishes.