The White House invoked executive privilege Wednesday, claiming the right to block lawmakers from the full report from special counsel Robert Mueller on his Trump-Russia probe and escalating the battle between President Donald Trump and Congress.

The administration's decision was announced just as the House Judiciary Committee was gaveling in to consider holding Attorney General William Barr in contempt of Congress over failure to release the full report.

Committee Chairman Jerrold Nadler of New York declared the action by Trump's Justice Department was a clear new sign of the president's 'blanket defiance' of Congress' constitutional rights. 'Every day we learn of new efforts by this administration to stonewall Congress,' Nadler said. 'This is unprecedented.'

White House Press Secretary Sarah Sanders said the action was rather a response to the 'blatant abuse of power' by Democratic Representative Nadler.

'Neither the White House nor Attorney General Barr will comply with Chairman Nadler's unlawful and reckless demands,' she said.

In a letter Wednesday to Trump, Barr explained that the special counsel's files contain millions of pages of classified and unclassified information. He said it was the committee's 'abrupt resort to a contempt vote' that 'has not allowed sufficient time for you to consider fully whether to make a conclusive assertion of executive privilege.'

Barr told Trump the president he should assert privilege now, 'pending a full decision on the matter.'

Democrats on the committee said the Trump administration was trampling on Congress's duty to conduct oversight.

'This is a moment in history,' said Representative Sheila Jackson Lee of Texas. 'The president now seeks to take a wrecking ball to the Constitution of the United States.'

But the top Republican on the panel, Representative Doug Collins of Georgia, called the majority's decision to push ahead with a contempt resolution 'cynical, mean-spirited, counterproductive and irresponsible.'

Nadler said earlier Wednesday the Trump administration's refusal to provide special counsel Robert Mueller's full Russia report to Congress presents a 'constitutional crisis,' leaving the panel no choice but to move forward with a contempt vote against Barr.

Talks with the Justice Department broke down late Tuesday over the committee's subpoena for an unredacted version of the report.

House Speaker Nancy Pelosi suggested Democrats were surprised by the department's decision as last-minute talks failed late Tuesday.

She said if the committee approves contempt resolution, as is expected, the 'next step' would be eventual consideration by the full House.

Barr released a redacted version of Mueller's report to the public last month, but Democrats said they want to see the full document, along with underlying evidence, and subpoenaed the full report. The department has rejected that demand, while allowing a handful of lawmakers to view a version of Mueller's report with fewer redactions. Democrats have said they won't view that version until they get broader access.

Executive privilege is the president's power to keep information from the courts, Congress and the public to protect the confidentiality of the Oval Office decision-making process.

The top Republican on the panel, Representative Doug Collins of Georgia, sharply criticized the Democrats' plan to go ahead with the vote.

'I can't imagine a more illogical hill for a legislator to die on,' Collins said in a statement.

If the committee holds Barr in contempt, it would be the first step in what could be a protracted, multipronged court battle between Congress and the Trump administration.

Trump has defied requests from House Democrats since the release of Mueller's report last month, and Democrats are fighting the White House on several fronts as they attempt to learn more about the report, call witnesses and obtain Trump's personal and financial documents.

In a related move, Nadler also threatened to hold former White House counsel Don McGahn in contempt of Congress if he doesn't testify before the committee later this month. Nadler rejected a White House claim that documents McGahn refused to provide despite a subpoena are controlled by the White House and thus McGahn has no legal right to them.

On Monday, Justice spokeswoman Kerri Kupec said the department has 'taken extraordinary steps to accommodate the House Judiciary Committee's requests for information' regarding Mueller's report, but that Nadler had not reciprocated. She noted that Democrats have refused to read the version of Mueller's report with fewer redactions that has been provided to Congress.

A contempt vote against Barr would head to the full House for a vote. If the House were to pass the resolution, it would send a criminal referral to the U.S. attorney for the District of Columbia, a Justice Department official who is likely to defend the attorney general.

Democratic House leaders could also file a lawsuit against the Justice Department to obtain the Mueller report, though the case could take months or even years to resolve. Some committee members have suggested they also could fine Barr as he withholds the information.

Republicans have largely united behind the president, with Senate Majority Leader Mitch McConnell on Tuesday declaring 'case closed' on Mueller's Russia probe and potential obstruction by Trump. McConnell said Democrats are 'grieving' the result.

Mueller said he could not establish a criminal conspiracy between the Trump campaign and Russia, but he did not reach a conclusion on whether Trump obstructed justice. Mueller didn't charge Trump but wrote that he couldn't exonerate him, either.

Pelosi and Senate Democratic leader Chuck Schumer issued a joint statement calling it 'a stunning act of political cynicism and a brazen violation of the oath we all take.'