WASHINGTON – It's way beyond saber-rattling.

Fights between President Donald Trump's administration and congressional Democrats investigating him headed to a showdown that could redefine the scope of presidential power against Congress' ability to rein in the chief executive.

Executive branch officials ignored subpoenas for documents and testimony. Lawmakers threatened officials, including Attorney General William Barr, with contempt. Trump carried two disputes into federal court to prevent release of his financial documents. The disputes are acrimonious enough that some frustrated lawmakers suggested jailing recalcitrant officials or impeaching Trump.

In a fraught and fractured capital, where it ends is anyone's guess.

Almost every president has found himself bridling against congressional oversight, but the confrontations usually reach a quiet and conciliatory end. The disputes between Trump and congressional Democrats, who regained control of the House in January, are so wide-ranging and heated, they have no obvious resolution.

“This feels different – it feels less like stage-setting for negotiation and more like 'I’m going to punch you in the face and take your lunch money,' " said Christopher Armstrong, a former general counsel to the Senate Finance Committee who led investigations and is in private practice at Holland & Knight. "And both sides want the other guy’s lunch money.”

Lawmakers traditionally threatened executive branch officials with subpoenas during disputes over documents and testimony, then negotiated a settlement. Trump has dug in against those demands, which he calls "presidential harassment," creating a standoff between two branches of the U.S. government.

The third branch of government – the federal courts – could ultimately referee that dispute but only after a legal battle that could stretch far beyond the end of Trump's presidency.

"That's precisely why people refer to this as a constitutional crisis," said Duncan Levin, a former federal prosecutor in New York. "I think we're living through a slow-motion constitutional car crash."

Past administrations usually found the costs of battling Congress over information to be too high and either caved or compromised, said Mark Rozell, dean of the Schar School of Policy and Government at George Mason University. The lack of cooperation should be "deeply concerning," he said.

“We are in a different environment right now where the two sides dig in, don't negotiate very effectively and end up playing zero-sum politics,” Rozell said. “It is extraordinary to even be having these discussions about levying fines or possible incarceration.”

At stake in six House investigations are the president's personal tax and business records, records of how White House security clearances were granted and details of a nearly two-year investigation into Russian interference in the 2016 election. The latest clash featured the Justice Department refusing Wednesday to comply with a subpoena for the full Russia report from special counsel Robert Mueller and the evidence gathered during his inquiry. That refusal came the same day Barr skipped a House hearing on the investigation over objections about how he would be questioned.

Judiciary Chairman Jerry Nadler, D-N.Y., said the panel would make one more negotiated effort to get the report, said the panel would make one more negotiated effort to get the report and then begin proceedings to hold Barr in contempt as early as next week.

Nadler said the president wants to prevent Congress from imposing "any check whatsoever" on his power.

“The challenge we face is that if we don’t stand up to him together, today, then we risk forever losing the power to stand up to any president in the future," Nadler said. "We will make sure that no president becomes a monarch."

House Speaker Nancy Pelosi, D-Calif., has tamped down talk of impeachment because even if the House approved charges, a two-thirds majority of the Republican-led Senate would be unlikely to remove Trump from office. But the impasse with the White House has whetted some lawmakers' appetites for a showdown, and Pelosi noted Thursday that one article of impeachment prepared against President Richard Nixon was for refusing to comply with congressional subpoenas.

“This is very, very serious,” Pelosi said.

House investigations of Trump

Six House committees are pursuing inquiries, and their demands have met escalating stages of resistance. In an exchange of letters, the Ways and Means Committee requested Trump’s tax returns, and Treasury Secretary Steven Mnuchin refused. The Oversight and Reform Committee subpoenaed financial documents from Trump’s longtime accountant Mazars USA, which the president is personally fighting in federal court. The Intelligence and Financial Services committees jointly subpoenaed Deutsche Bank, a longtime lender to Trump, for financial records, and the president is fighting that release in another lawsuit.

“The executive branch has decided that it doesn’t have to cooperate with Congress,” said Rep. Jamie Raskin, D-Md., a former professor of constitutional law who serves on the Judiciary and Oversight panels. "The obstructionism that we read about in the Mueller report has come galloping off the pages and right onto our front doorstep.”

The requests have largely been a partisan exercise. Republicans in Congress joined in few of them and largely dismissed many as attempts to target the president.

“I don’t know any fair-minded person who believes that the House is doing anything but trying to harass the president of the United States,” said Sen. John Kennedy, R-La. “We all get to vote in two years. In the meantime, they need to accept the judgment of the American people, which is sovereign, and let the president be president.”

For want of a better solution, many of the disputes are on track to end up in court.

“I think right now we’re staring at the challenge in front of our face, which is how do we enforce the subpoenas,” said Rep. Raja Krishnamoorthi, D-Ill., a member of the Oversight committee. “The courts, including the Supreme Court, have upheld Congress’s right to investigate, issue subpoenas and hold people in contempt. If they want to litigate, we’ll see them in court.”

Trump said April 24 that his administration would fight subpoenas and stop having officials testify at hearings because the requests fuel political attacks.

The congressional inquiries have nettled Trump after Mueller found no conspiracy between his campaign and Russians who interfered in the 2016 election to help him win. Mueller cited 10 episodes of potential obstruction of justice during his inquiry, but Barr decided no charges were warranted.

Besides subpoenaing the Mueller report, the House Judiciary Committee panel subpoenaed former White House counsel Don McGahn, who is key to several episodes of possible obstruction. Trump said Thursday he would block McGahn's testimony under a claim of executive privilege, which protects candid advice from advisers.

One of those conflicts came to a quiet end this week. House Oversight Chairman Elijah Cummings, D-Md., subpoenaed a White House security official, Carl Kline, on April 2 for testimony about how security clearances were granted and threatened contempt proceedings after Kline didn't show up for a deposition. The panel's top Republican, Rep. Jim Jordan of Ohio, a fierce defender of the administration, urged the White House to "avoid unnecessary conflict" and allow Kline to testify, and the White House allowed him to appear in a closed session.

Contempt and the courts

Congress has a variety of tools to compel the administration to provide documents and testimony, including subpoenas, contempt citations that could carry either criminal or civil penalties or even incarceration. Each is cumbersome and has drawbacks.

Traditionally, the threat of a subpoena prompted the administration to negotiate a settlement for fewer documents or a different format for testimony. If still at loggerheads, lawmakers on rare occasions hold officials in contempt, asking the Justice Department to file criminal charges or filing a civil lawsuit to demand information. The limits of those options are illustrated in three major cases during the past 35 years:

• The House voted in 2008 to hold Harriet Miers, a lawyer for President George W. Bush, in contempt after she refused to turn over documents about the president's dismissal of nine U.S. attorneys. Lawmakers voted to refer her for prosecution and to launch a civil lawsuit to enforce the subpoena. The Justice Department refused to file charges. The dispute was settled more than a year later when Miers testified at a closed hearing.

• The House held Attorney General Eric Holder in contempt in 2012 for refusing to turn over records about Operation Fast and Furious, which resulted in thousands of guns being smuggled to drug cartels in Mexico. Holder's deputy, James Cole, notified the House that Holder wouldn't be prosecuted because his response to the subpoena “does not constitute a crime.” The committee filed a federal lawsuit in August 2012 to enforce the subpoena, which dragged on for more than six years.

• Lawmakers voted to hold former IRS official Lois Lerner in contempt in 2014 after she asserted her Fifth Amendment rights and refused to testify in an investigation about the tax agency improperly targeting conservative groups. The Justice Department declined to prosecute her.

Taking the other side to court can sound like decisive action and a sure way to end a dispute. But the arguments can take years and lead to unpredictable results as each branch of government jockeys against the others.

"Aggressive assertion of congressional prerogatives – and aggressive defenses of the president’s privileges – are both a healthy and necessary part of our constitutional order," Armstrong said.

Lawmakers grapple with options

Congress could take more direct action.

Congress has an "inherent contempt" power, which gives it the ability to enforce its own subpoenas by locking up witnesses if necessary. From 1795 to 1857, the House and Senate initiated 14 inherent contempt actions and meted out punishment in eight cases, according to the Congressional Research Service.

Some Democrats have become so frustrated that locking up reluctant witnesses sounds like an option. “We recognize the president’s strategy is to drag this out in litigation, which I think makes that final process maybe the one that Congress has to do," said Rep. David Cicilline, D-R.I.

Congress adopted a criminal contempt law in 1857, and in the Watergate era, it began enforcing its subpoenas by bringing civil lawsuits in federal court. Congress never renounced its power to take matters in its own hands. During an investigation in 1879, George Seward, who was consul general in Shanghai, refused to comply with a request for documents and testimony. The sergeant-at-arms took him into custody, and he was brought before the House, then immediately released while lawmakers considered articles of impeachment.

Rep. Ted Lieu, D-Calif., a vocal Trump critic on the Judiciary Committee, said Congress could avoid the courts and "start imposing fines," and he noted there is "a House jail."

"I don't think we're going to go that far, but courts have upheld that as well," Lieu said. "Congress' power will not be abdicated."

Beyond compelling testimony, the House could pursue impeachment, the political equivalent to indicting Trump. House leaders such as Pelosi and Nadler have downplayed that option, but some of their fellow Democrats have embraced it, particularly as the administration stymied other types of oversight.

“I just do not believe, as a former law enforcement officer, that the president of the United States can do anything that he wants to do and not be held accountable,” said Rep. Val Demings, D-Fla., a former Orlando chief of police. “But special counsel Mueller, believing that, I think left a road map for Congress to follow, and that would be impeachment.”

More about congressional investigations and the Trump administration:

'We're fighting all the subpoenas.' Congress and Trump prepare to battle over wide-ranging inquiries

AG William Barr warns he could refuse to appear at House hearing on Mueller report, objecting to format

President Trump still facing swirl of investigations even after Robert Mueller's inquiry ended