President Donald Trump’s increasingly bitter clashes with Congress aren’t just infuriating Democrats and sparking talk of impeachment. They are setting new precedents for the exercise of presidential power and authority that could change Washington for years to come.

Past presidents have certainly fought with Congress and invoked executive privilege. They include Trump’s predecessor, President Barack Obama. But Trump has suggested that he doesn’t consider Democratic congressional oversight itself to be legitimate, and is resisting it on multiple fronts at once.

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Trump’s actions over 72 hours this week have been dramatic: They include the assertion of executive privilege over the full Mueller report, a refusal to hand over his tax returns, and a move to block his former top White House attorney from testifying before the House. They follow multiple lawsuits he has filed — including against a House Democratic committee chairman — to block the release of personal financial records. He has done it all with the chin-out defiance Trump made his trademark during years of legal battles as a New York real estate mogul.

Taken together, the moves are part of a larger posture of defiance by a president who has flaunted countless norms, including those governing congressional prerogatives and oversight. Democratic lawmakers and nonpartisan congressional experts say Trump is writing a playbook for future presidents to ignore Congress’ requests — with the caveat that this ultimately still must play out in the courts.

“This creates a terrible precedent,” said Charles Tiefer, former deputy general counsel of the U.S. House of Representatives for 11 years and a professor at the University of Baltimore Law School. “There is a general effect that each president starts out from the level of resistance of the prior president. Trump is raising the bar, and the next president will have that as his model.”

Democrats sound even more dire alarms. “This is unprecedented,” House Judiciary Chairman Jerrold Nadler said during a committee session Wednesday, after learning that the Trump White House was blocking lawmaker access to the full Mueller report on executive-privilege grounds. “If allowed to go unchecked, this obstruction means the end of congressional oversight.”

But the concern doesn’t come only from Democrats, whom Trump accuses of having a politically motivated and therefore invalid agenda. When Trump ended this winter’s government shutdown by invoking a state of emergency to access money for a Mexican border wall that Congress would not allocate him, even many Republicans warned that that Trump was setting the stage for a Democratic successor to follow suit. Their fears were inflamed in February when the Democratic House Speaker, Nancy Pelosi, suggested that a future Democratic president could declare a national emergency to tackle gun violence.

Trump himself betrays no concern about overreach, according to fellow Republicans. While his lawyers assert constitutional grounds for his actions, people close to the president say that he thinks in very different terms.

“These aren’t, like, impartial people,” Trump said last month after declaring that he was “fighting all the subpoenas” from the House.

“His attitude is, you’re not playing ball with me, I won’t play ball with you,” said one Republican close to the White House. “You said something nasty last night, so screw you. He’s in that mode and it’s very hard for him and he doesn’t have people around him to talk him out of doing that now.”

While Democrats firmly opposed Trump’s February national emergency declaration, they are raising louder alarms about his stiff resistance to oversight efforts by several House committees.

“There’s always a tension between the two branches, but I think this has reached a record level where the president won’t disclose his tax returns and basically refuse to testify before Mueller and now he’s saying there’s just going to be no communication,” said Democratic Sen. Richard Durbin, one of the Senate’s highest-ranking members.

Senior Trump aides believe that Democrats’ aggressive oversight amounts to little more than a campaign to ensure the president doesn’t get reelected. They insist privately that what Trump is being subjected to is unlike anything in recent history.

In interviews, multiple White House officials dismissed the notion that the Trump administration is setting a damaging precedent.

“We’re already way past niceties and precedent,” said Kellyanne Conway, a senior Trump adviser. Asked whether she worries that a future Democratic president could employ the same tactics against a Republican Congress, Conway argued that it is the House Democratic requests that are unprecedented.

“I guess you’re conceding that we can investigate them for nonsense too,” she shot back.

“The Trump Administration has accommodated and will continue to accommodate reasonable congressional oversight requests,” said White House spokesman Steven Groves. “House Democrats, however, habitually demand documents and information they have no legal right to obtain. The White House will continue to protect the interests of the Executive Branch against unlawful congressional overreach.”

Other Republicans dismissed the idea that the White House and Congress have entered uncharted or precedent-setting territory.

“The relationship between the two branches of government has deteriorated over the past decade or two, but it is not worse now than it was when Holder was held into contempt. I don’t think it is necessarily related to Trump. It was not that good before,” said C. Boyden Gray, the former White House counsel under President George H.W. Bush and the founding partner of the law firm, Boyden Gray & Associates.

Veterans of past White Houses say the congressional oversight the Trump administration is grappling with is hardly a new phenomenon.

The Obama administration, for example, faced a steady barrage of investigations from House Republicans on everything from the Energy Department’s loan guarantee to the solar company Solyndra to the Operation Fast and Furious gunwalking probe. And in 2012, the House voted to hold then-Attorney General Eric Holder in contempt of Congress for his failure to turn over documents related to the so-called Fast and Furious probe. That was the first time the House went after a Cabinet official in such an aggressive manner.

“Former House Speaker John Boehner (R-Ohio) also extolled the constitutional value of oversight, but saw investigations as a way to dismantle government, not improve it,” wrote Paul Light, a professor of public service at New York University in a recent study of past House investigations. “Boehner weaponized the investigatory process for maximum political damage.”

In 2007, the George W. Bush administration also faced serious challenges from Congress and tried to bar then-ex White House counsel Harriet Miers from testifying about the firing of U.S. attorneys. Bush, too, asserted executive privilege. Some experts have compared that episode to Trump’s efforts to prevent former White House counsel Don McGahn from complying with a congressional subpoena.

However, this political moment is different because the high-profile clashes between the executive and legislative branches are happening on multiple fronts at the same time, experts said.

“What I don’t think has happened before is having them all happen at once,” said Andy Wright, a partner at the firm K&L Gates who served as an Obama White House lawyer and a lawyer for Vice President Al Gore.

The Trump White House’s strategy could set a political precedent that would pave the way for future administrations to wholly reject Congress’ requests and subpoenas, Wright said. But the real test will come in the courts, which will determine whether Trump’s strategy is successful.

“What is happening here is there is a rush to the court and a rush to get decisions, and they could set some really difficult precedents down the line,” said Justin Rood, who directs the Project on Government Oversight’s Congressional Oversight Initiative and who previously worked under Republican Sen. Tom Coburn for the Homeland Security and Government Affairs Committee.

But in a sign of these extremely partisan times, Democrats and Republicans hold wholly different takes on the White House’s latest responses to congressional inquiries. Republican lawmakers still remain firmly behind the president including in the Senate, where they hold the majority.

“I’m not concerned about this setting a precedent. I’m just not,” said Sen. Josh Hawley of Missouri who previously served as Missouri’s attorney general. “I mean every president evaluates whether he or someday she wants to invoke executive privilege. That’s going to happen no matter who is president.”

Many conservatives also believe that this back-and-forth between the White House and House Democrats ultimately will not register with voters heading into the 2020 presidential campaign.

“I don’t believe the average voter in Iowa or Ohio cares very much about this, and the candidates who are running are not jumping into the debate about whether Barr should testify before staff or members,” said Gray, the former White House attorney.

Andrew Desiderio, Marianne Levine, and Daniel Lippman contributed to this story.