Washington (CNN) Donald Trump's stonewalling White House is mounting a multi-front assault on accountability, testing the notion that a president must answer to citizens for whom he holds a public trust.

Trump has spent his entire presidency rebelling against rules that have largely constrained most of his predecessors. Many are not written in law but have been seen as accepted codes of presidential conduct, making it easier for him to trample them.

Bulldozing tradition, Trump either ignores or defies established practices of governance and personal transparency, seeking to maximize his personal influence and consolidate power inside the White House while resisting outside scrutiny.

"The context in which this is happening raises some serious questions about the willingness of the White House to honor long understood norms of democratic governance," said Rudy Mehrbani, senior counsel at the Brennan Center for Justice.

In the latest show of defiance, the White House may seek to prevent former White House counsel Don McGahn from complying with a subpoena issued by the House Judiciary Committee that demands his cooperation in its probe into potential obstruction of justice.

In an interview with The Washington Post on Tuesday, Trump made it clear that he has no designs on cooperating with investigations led by House Democrats -- expressly saying he doesn't want his current or former aides testifying to Democrat-led panels.

"There is no reason to go any further, and especially in Congress where it's very partisan -- obviously very partisan," he said.

"I don't want people testifying to a party, because that is what they're doing if they do this," Trump added.

"Although federal law establishes no deadline for a response to your request, we expect to provide the Committee with a final decision by May 6, after receiving the Justice Department's legal conclusions," Treasury Secretary Steven Mnuchin said in a letter to House Ways and Means Chairman Richard Neal.

Democrats argue there is zero legal latitude for the administration to dispute a federal law that states that the Treasury "shall" furnish three designated congressional officials with any individual's tax information.

Trump's attorneys are seeking an injunction to block another House committee from compelling his accountancy firm to hand over documents related to his business empire.

And the White House just ordered a subpoenaed former senior official not to show up at a hearing of a House panel investigating the security clearance process for top officials.

"Based on these actions, it appears that the President believes that the Constitution does not apply to his White House, that he may order officials at will to violate their legal obligations, and that he may obstruct attempts by Congress to conduct oversight," said House Oversight Chairman Elijah Cummings.

Amid a flurry of oversight that was missing during the days of the plaint GOP majority before the midterm elections, Democrats also just issued a subpoena for McGahn to testify about possible abuses of power by the President unveiled last week in the Mueller report

"They don't want to get to the truth, they want to get to this President," White House deputy spokesman Hogan Gidley said earlier Tuesday amplifying the White House argument that Democratic demands have nothing to do with oversight but are simply an example of unfair "presidential harassment."

Latest challenges

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This quartet of disputes merely represent the latest challenges to the idea that the White House should be accountable to Congress, and the voters lawmakers represent, in just the last few days.

They are a small sample of numerous assaults the administration has made against accountability, starting with Trump's refusal to be more open about his finances, including his management of foreign policy and the way his White House snubs another organ of scrutiny -- the media.

The President has, by The Washington Post's count , now lied more than 8,700 times in office — often to avoid the consequences of his own actions and statements.

He's made disputed claims of executive power to build his border wall when Congress declined to finance it in open defiance of the constitutional understanding that it is lawmakers, not the President, who have the power of the purse. As the Mueller investigation showed , Trump has ordered subordinates to lie to the press and the Pentagon, the White House and State Department now rarely give regular briefings.

In July 2017, beset with questions about the Trump team's mysterious contacts with Russians during the campaign the previous year, White House spokeswoman Sarah Sanders said "every day we do our best to give the most accurate information we have."

"Our goal is to be as transparent as humanly possible."

Yet only a few months earlier, as has now been revealed by Mueller, Sanders lied to White House reporters when she said "countless" FBI agents told her they were thankful the President fired former FBI Chief James Comey.

There are many less public infringements of transparency.

Reports and revelations about cozy relationships between Trump Cabinet appointees and industry lobbyists contradict the President's claim that he's draining the Washington swamp.

His employment of family members raises questions of nepotism, and he has refused a bipartisan effort by the Senate to provide a report on the murder of Washington Post columnist Jamal Khashoggi in the Saudi consulate in Istanbul.

The President's son-in-law Jared Kushner epitomized the administration's attitude to accountability when he declared Tuesday that investigations "had a much harsher impact on our democracy" than Russian election meddling.

And Trump has made little secret of the fact that another of his efforts to make an end-run around Congress -- his preference for "acting" Cabinet members who are not confirmed -- is designed to maximize his own power.

"I sort of like 'acting,'" Trump told reporters in January. "It gives me more flexibility; do you understand that? I like 'acting.'"

The failure to confirm Cabinet officers -- like acting Defense Secretary Patrick Shanahan or acting Interior Secretary David Bernhardt -- does not just repudiate the Senate's constitutional advise-and-consent function. It drains power from their agencies and hammers morale among the public servants who devote their careers to government.

Some confrontations are constitutional

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Confrontations between a President and Congress are written into the US constitutional system, and in many ways are a sign that the system of shared political power is working properly.

President Barack Obama's Attorney General Eric Holder was held in contempt of Congress by the then Republican House for failing to hand over documents relevant to the Fast and Furious scandal over illegal gun sales. President George W. Bush dueled with Congress after trying to block public testimony from top aides over a controversy about the firing of federal prosecutors.

There are also often legitimate disagreements between a president and Congress on the division of powers and executive privilege.

But the scale of Trump's refusal to comply with basic norms of transparency is so endemic that it is stoking fears that Trump could establish precedents that reshape the principle of checks and balances enshrined in the Constitution.

The escalating legal trench warfare between Democrats is at its root a tussle over the extent to which a president has an obligation to voters to be above reproach and suspicion.

Trump has shown he's not got much time for such rituals.

His insult to transparency started before he took office, as he refused to bow to demands that he release his tax returns -- a tradition followed by presidential nominees for decades.

Trump then refused to fully divest himself from his family business empire, to assure Americans his economic and national security decisions would not pose a conflict of interest.

That omission led to a case working its way through the courts that charges that the President's failure to give up ownership of his Washington hotel violates the emoluments clause of the Constitution that prohibits officials from receiving gifts or payments from foreign states. It's possible Trump could be vindicated -- but it's also impossible to imagine any other president would put himself in such a position.

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Trump's newest legal battle, to stop the release of business records from his accounting firm , effectively involves an effort by the executive branch of government to thwart constitutionally protected oversight.

The committee wants the records to investigate claims by Trump's former lawyer Michael Cohen that his former boss used financial statements either to inflate the price of business assets to get loans or downplayed property values in insurance schemes.

Trump Organization counsel Alan Garten called the subpoena "an unprecedented overreach of congressional authority."

But the challenge by Trump and his sons, who now run the business, shows no recognition that when someone assumes a public trust, such as the presidency, they also face standards of transparency they would not face in public life.

In sending his lawyers into action, the President is again activating the kind of litigating reflex which he often indulged as a tycoon when he was party to thousands of lawsuits.

But his chances of thwarting the House committee may be slim since his attorneys are relying on a precedent from the 1880s that was superseded by a decision in 1927.

And Trump's legal team often seems to be seeking retroactive rationales for decisions made by Trump on the fly.

"I think if you look up the word desperation in the dictionary I think you get a picture of Trump's legal team as they try desperately to follow the whims of the boss," said former federal prosecutor Shan Wu, who is not a CNN legal analyst.

Trump's resistance to scrutiny by Congress especially may be an issue that outlives this current, testy period of his presidency. Some analysts fear that it could provide a precedent for future Presidents -- even those who are less instinctively programmed to test norms as Trump -- to exploit.

"What we are learning from Trump is that there is abundance of mechanisms that had existed within the executive branch and they were followed not because they were required by law because of past precedents and the expectation they would be followed," said Mehrbani.

"If that expectation no longer exists, then the potential for abuse is significant so I think Congress is obligated to respond."