WASHINGTON (AFP) - US House Democrats scheduled a Wednesday (May 8) vote on whether to hold Attorney General Bill Barr in contempt for failing to produce a full, unredacted special counsel's report on Russian election interference.

Monday's dramatic move against a sitting cabinet official, following multiple subpoenas issued to Barr, intensifies the showdown between President Donald Trump and the Democrats who control the House of Representatives and are seeking to hold him to account for what they say was improper conduct.

"The attorney general's failure to comply with our subpoena, after extensive accommodation efforts, leaves us no choice but to initiate contempt proceedings in order to enforce the subpoena and access the full, unredacted report," House Judiciary Committee chairman Jerry Nadler said in a statement, after a missed 9am (9pm Singapore time) deadline.

The committee scheduled a legislative process, known as a markup, to consider a contempt report against Barr beginning at 10am Wednesday that will see members debate and then vote on the resolution and supporting report.

Should the committee vote to accept the report, it proceeds to a full House vote.

Nadler said he reserved the right to postpone the action should the department present a "good faith offer" for access to the full report and evidence.

Barr had declared Trump fully cleared of conspiracy with Russia and obstruction of justice shortly after special counsel Robert Mueller presented his 448-page report to the Justice Department.

But Democrats have protested that Barr has sought to protect the president by refusing to present the full report or underlying evidence to Congress.

In a 27-page contempt report, Nadler said House Speaker Nancy Pelosi, Trump's chief nemesis in Congress, is empowered to "take all appropriate action to enforce the subpoena."

'Constitutional duty'

Such actions may include fines against the attorney general or even arrest, although such action is unlikely.

Congress is "the only body able to hold the president to account for improper conduct in our tripartite system, and urgently requires the subpoenaed material to determine whether and how to proceed with its constitutional duty to provide checks and balances on the president and executive branch," Nadler wrote.

"Access to these materials is essential to the committee's ability to effectively investigate possible misconduct, and consider appropriate legislative, oversight, or other constitutionally warranted responses."

The statement is clear reference to the potential for impeachment proceedings against Trump if House leadership believes they are warranted.

Pelosi has warned against moving ahead with impeachment, suggesting it could trigger a political backlash, and that the Republican-controlled Senate would be unlikely to convict the president.

But Barr's stonewalling, and the report's setting forth of 10 instances in which Trump sought to thwart the investigation - although Mueller did not reach a conclusion on whether crimes were committed - has galvanized support among some Democrats to demand Trump's ouster.

Top Judiciary panel Republican Doug Collins signalled that the Justice Department was still negotiating over Nadler's request, and that the contempt move is "illogical and disingenuous." "Democrats have launched a proxy war smearing the attorney general when their anger actually lies with the president and the special counsel, who found neither conspiracy nor obstruction," Collins said.

Holding a sitting US attorney general in contempt is rare. A Republican-led House held Barack Obama's attorney general Eric Holder in contempt in 2012 for failing to turn over documents about a firearms scandal.

Democrats have also called for Mueller to testify, with Nadler wanting the special counsel to appear before his committee on May 15.

But Trump put his hand on the scale Sunday, saying "Bob Mueller should not testify." Bernie Sanders, a frontrunner in the 2020 Democratic nominations race, levelled a scathing rebuke.

"Sorry, Mr President, you are not a dictator," the liberal senator posted on Twitter. "In our democracy, when Congress calls on Robert Mueller to testify, he will testify." The White House is facing a flurry of investigations.

After the US Treasury failed to meet a deadline to turn over Trump's tax returns to House Democrats, it said last month that it will take a "final" decision by May 6 about whether to provide the data.