The constitutional conflict between congressional Democrats and President Trump accelerated sharply Wednesday, as the White House blocked access to potentially damaging information in special counsel Robert S. Mueller III’s work and lawmakers declared the standoff had become a crisis.

For the first time during the Trump administration, the president asserted executive privilege over material demanded by Congress — saying it was necessary to avoid complying with a House Judiciary Committee subpoena that Justice Department officials said could violate the law and weaken prosecutors’ independence.

The committee, led by Rep. Jerrold Nadler (D-N.Y.), voted to hold Attorney General William P. Barr in contempt of Congress over his refusal to furnish an unredacted copy of Mueller’s report. Justice Department officials had announced hours earlier that the president had asserted privilege over Mueller’s report.

On the surface, the fight over an unredacted copy of Mueller’s report — and its underlying investigative documents — hinges on disagreements over the law surrounding grand jury material and legal precedents. But at its heart, Wednesday’s dispute is about the seemingly in­trac­table conflict between House Democrats, who are seeking a public airing of damaging details about Trump, and the president, who has vowed to give them nothing.

The two sides now appear headed for a court fight over the balance of power between the executive and legislative branches, and at a faster pace than previous legal battles over executive privilege. Each appears to be proceeding with an eye on how such a conflict might play out in the 2020 race for president and the possibility, however faint, of impeachment proceedings.

“It’s getting kind of hectic,” said Robert Raben, a senior Justice Department official during the Clinton administration, who characterized their power struggle as an “asymmetrical” fight.

“The White House and their Republican supporters have a strategy of omerta, the code of silence, and everybody has to abide by it,” said Raben. “The strategy on the left is regular order: These are the rules, and what happened to the rules?”

Raben said that while Barr, having been the attorney general for only a few months, may “set a world indoor record for contempt proceedings, I don’t think this is tectonic plates bumping up against each other. It’s two different trajectories, and Trump could run out the clock. It’s a long clock, but he could do it.”

In past administrations, conflicts over congressional access to White House documents and witnesses have often dragged on for a year or longer before reaching this stage of impasse.

For instance, when President Obama’s attorney general Eric H. Holder Jr. fought House Republicans for more than a year over documents related to a botched gunrunning probe called Fast and Furious, it took more than a year for that conflict to crescendo into a 2012 House vote to find him in contempt.

With the Mueller report, it took only weeks to reach the state, and may serve as an important test case for ongoing fights between the White House and Congress.

House Democrats have been rebuffed in their demands for Trump’s tax returns, a hearing with former White House counsel Donald McGahn and records related to how security clearances were granted to senior Trump aides.

The standoff also could have consequences for Democrats’ demands to obtain public testimony from Mueller. They have urged Mueller to appear quickly before Congress and testify about his investigation and his interactions with Barr, but no hearing is scheduled.

Senior House Democratic aides said they have concluded Trump will not turn over information, so negotiations are unlikely to be fruitful.

“We have to show people that is a blanket stonewalling of the public’s right to know,” one person involved in Democratic strategy discussions said. Some Democrats believe the president’s continued refusals ramp up the chances of an impeachment inquiry, a senior aide said, but party leaders remain skeptical of beginning such an inquiry given the odds they are unlikely to be successful. The person involved in Democratic strategy discussions and the senior aide spoke on the condition of anonymity to describe internal discussions.

Legal experts view the White House’s move as a clever, if risky, way to stall a possible reckoning in court. Barr recommended to Trump that he make a “protective” assertion of executive privilege, meaning a broad claim of his authority as president that later could be narrowed as government lawyers review the material Democrats are seeking.

As precedent, administration lawyers cited a protective claim of privilege over Clinton administration records subpoenaed by the Republican-led House seeking information about the firing of White House travel staffers.

Joshua Geltzer, executive director of Georgetown Law’s Institute for Constitutional Advocacy and Protection, said he was skeptical the Trump administration believes it needs more time to fulfill the Democrats’ requests for documents, interviews and investigative materials.

“This is a stalling tactic,” Geltzer said, adding that he thought the administration’s stated need for more time was dubious, given that Barr already claimed to have fully reviewed the Mueller report.

Nevertheless, the White House’s claim of executive privilege has legal power because it relies on past practice for the two branches of government to negotiate until they reach an accommodation.

“The protective privilege is a way to kick that can down the road time-wise and benefit from an exaggeration of what’s really privileged,” Geltzer said.

Buying time for the Trump administration may have long-term legal risks, both for this administration and for future presidents, but it could help Trump politically.

Keeping damaging information or testimony out of public view for an extended period could aid the president’s reelection chances. But if the president were to lose in court, that could weaken every future presidency that sought to keep its internal discussions private.

Walter Dellinger, who oversaw the Justice Department’s Office of Legal Counsel during the Clinton administration, said he considers the Trump administration’s claim of a protective assertion justified at this stage.

“It could well be that in the millions of pages being sought, there are materials for which there is a genuine claim of executive privilege,” Dellinger said. “This assertion may be necessary to gain time for that review.”

But Dellinger warned that the White House has to back it up with good faith, by conducting a speedy review. And even if it does, the White House could still lose in court.

“The White House has seriously compromised their position in court by asserting that it will claim executive privilege against all requests for documents and testimony from the House,” Dellinger said. “That will seriously undermine the assertion of a good-faith effort to review these materials.”

While the White House could win some fights over documents, Dellinger doubted they could prevail on preventing McGahn or Mueller from testifying. “That seems to be a great leap,” he said.

Historically, most fights between the executive and legislative branches in government that end up in court tend to be resolved through a compromise before a high-court ruling locks in either side for the foreseeable future.

Trump’s gambit seems to present a different tactic — a willingness to let the high-stakes question of congressional oversight be settled by an appeals court, or even the Supreme Court.

White House officials say that Trump may assert executive privilege again if the Democrats continue to push McGahn for documents — and that it makes the most sense to do so just before any contempt filing, as he did Wednesday.

Trump considered asserting executive privilege on parts of the Mueller report before it was released last month, but advisers — including officials in the White House Counsel’s Office — warned him of the political perils of appearing to stonewall and give more fuel to accusations of a coverup.

Trump does not want McGahn or any other former White House official to testify on Capitol Hill and has told lawyers to take necessary steps to block requests for testimony or documents, according to people familiar with internal White House discussions who spoke on the condition of anonymity because of the matter’s sensitivity.

Jack Quinn, former counsel to Bill Clinton during an independent counsel investigation of the former president, said that Wednesday’s assertion of privilege by the White House could backfire over the long run.

“They are doing it so broadly and with so little judgment that I think they are debasing their overall approach to this,” said Quinn, suggesting a judge may come to view Trump’s position as untenable. “The overreliance on executive privilege in the end will be problematic for the White House.”

Quinn said Democrats must frame their requests as part of a review to determine if Trump committed impeachable offenses.

“There is absolutely no constitutional way they can block the impeachment powers granted to the House,” said Quinn.