President Donald Trump, while portraying himself as the victim in a political war, is foiling an aggressive House Democratic majority’s investigations with historic fervor by refusing to comply with many subpoenas and other oversight requests.

On one level, this is nothing new. Prior Congresses and White Houses have certainly found themselves at odds over how much information to disclose. But the blanket defiance of the Trump administration has reached a new level of obstruction in recent days.

“That’s about as blatant an obstruction of the lawful processes of a coequal branch of government as I’ve ever seen,” Laurence Tribe, a Harvard constitutional scholar, told the Washington Post’s Jennifer Rubin recently.

According to Politico, citing House Democratic sources, the Trump administration has denied or delayed the release of information sought by Democratic committees on more than 30 occasions, and half a dozen administration officials have refused to appear before House panels.

The dispute headed to court when Trump’s personal attorneys sued Oversight Committee Chair Elijah Cummings over Cummings’s subpoena of Trump’s accounting firm seeking his personal financial records. The next day, the administration missed a deadline to turn over Trump’s tax returns requested by the House Ways and Means Committee, and the president himself called the Washington Post’s Robert Costa to say he didn’t want White House aides — like former aide Carl Kline, recently subpoenaed and now at risk of contempt of Congress proceedings — to testify before a House panel.

Trump indicated to the Post he had done all he needed to do by cooperating with special counsel Robert Mueller (who notably probed whether Trump obstructed justice and left the question of whether he had to Congress). The White House also said it plans to fight a Democratic subpoena of former White House counsel Don McGahn, a critical figure in the Mueller saga.

“There is no reason to go any further, and especially in Congress where it’s very partisan,” Trump told Costa. He later told reporters the White House would fight “all the subpoenas” coming from Democrats.

Trump’s lawyers are making the same argument in federal court, attempting to quash a subpoena from Cummings asking the Mazars accounting firm for eight years of personal and business records from the president’s file. That case will get a hearing on May 14 before federal judge Amit Mehta.

Accusing House Democrats of launching an “all-out war,” the president’s attorneys assert that the subpoena’s objective is ”to expose [Trump’s] private financial information for the sake of exposure with the hope that it will turn up something that Democrats can use as a political tool against the President now and in the 2020 election.”

House Democrats were transparent about their intention to aggressively investigate Trump after they took power, arguing the prior Republican majority had given the president a free pass. According to Trump’s lawyers, Democrats have issued more than 100 subpoenas and other requests for information from the president and his associates.

The White House’s response has been to provide as much resistance to that congressional oversight as possible. Even on requests that are eventually acquiesced to, Democratic aides told me the administration will often slow-roll those queries or provide nonresponsive answers.

Trump has defied the conventional norms of transparency that we expect from our presidents since before his election. In this latest escalation, he’s been willing to entertain a constitutional crisis to continue withholding information from Democratic lawmakers.

Trump has defied a remarkable number of congressional subpoenas and requests

Cummings, as head of the oversight panel, has taken the lead in investigating the Trump administration and thereby put himself at the center of the fight over what information the executive branch is required to hand over to the legislative. In March, the Congress member wrote in an op-ed in the Washington Post that his committee had sent at least 12 letters in pursuit of records from the administration and all of those requests had been ignored so far.

The Oversight Committee is probing the White House’s issuance of security clearances to Jared Kushner and other officials, the Stormy Daniels “hush money” payments, and other controversies. But they have received little cooperation from Trump and his subordinates.

“The White House is engaged in an unprecedented level of stonewalling, delay and obstruction,” Cummings wrote in the Post.

Trump has been particularly vigilant about safeguarding details of his financial health. In addition to the lawsuit over Cummings’s subpoena, Trump Organization lawyers have said they will also fight to block the enforcement of a subpoena from the House Intelligence and Financial Services committees soliciting information from Deutsche Bank.

Much of the stonewalling has come on high-profile matters potentially embarrassing for Trump, like his tax returns or lines of inquiry related to the Mueller investigation. Trump is already fighting those subpoenas issued to financial institutions that hold his confidential records. House Judiciary Committee Chair Jerry Nadler subpoenaed McGahn, who figured prominently in Mueller’s investigation into the president’s possible obstruction of justice, and now the White House will try to prevent McGahn from testifying, per Politico.

But the Trump administration has proven obstinate on more obscure issues as well. The House Energy and Commerce Committee sought safety studies from the Environmental Protection Agency about a chemical, Pigment Violet 29, commonly found in paints and plastics.

The EPA refused the request, claiming that the studies contained confidential business information, a decision Democrats strongly dispute under the law governing the disclosure of such studies. The agency has often been criticized for its coziness with the industries it regulates.

Trump has fostered a culture of secrecy since before his election

Trump defied a generation of political norms when, during the 2016 presidential campaign, he refused to release any of his personal tax returns. He claimed an ongoing audit prevent his releasing any tax records — even though, as Vox’s Matthew Yglesias noted at the time, there is no law prohibiting a person under audit from publicizing their returns.

Those tax records not only would have put Trump’s claims of remarkable business acumen under scrutiny but also would have revealed any potential conflicts of interest — with, for example, the Russian kleptocracy that has bedeviled the president since before he entered the Oval Office. From Yglesias:

Trump’s statements about NATO and the leak of Democratic National Committee emails likely pilfered by Russians have raised questions about Trump’s financial relationships with oligarchs tied to the Russian government. Tax disclosure would let us see how Trump’s businesses work — how successful he really is and how much that success hinges on investments from foreign actors who may have a more nefarious agenda than real estate development.

But Trump won the election, paying no political price for his lack of transparency. He has maintained the same stance since taking the oath of office. Democrats have tried all kinds of creative ways to open the hood on Trump’s finances — from the congressional inquiries to a lawsuit over Trump’s Washington hotel and possible corruption in the payments being made to the president’s business by parties with active interests before the White House. There was also the Mueller investigation, though it has since come to an end without scoring some of the big disclosures.

But Democrats have new power to force disclosure on Trump. For the first two years of his presidency, he didn’t have to worry much about the Republican-controlled Congress probing his business ventures or the agenda being set by his administration. But with Democrats taking back the House on a message of putting a check on Trump, he’s been the target of a much more aggressive legislature.

Trump has set a culture of secrecy that rivals Richard Nixon. He won’t release his financial records. He has been investigated for obstructing justice by Robert Mueller. Now he doesn’t want administration officials testifying in Congress, one of the most routine and sacrosanct examples of the country’s systems of checks and balances. In court, Trump’s lawyers have made a sweeping case to curtail Congress’s ability to investigate the executive branch.

This kind of dispute is not totally new. George W. Bush’s administration sought to stop Harriet Miers from testifying before House Democrats as they investigated the firing of US attorneys during his tenure. Obama Attorney General Eric Holder was held in contempt of a Republican House panel after he refused to turn over all the information requested by lawmakers relating to the so-called Fast and Furious scandal.

As former House counsel Stanley Brand put it on the Lawfare podcast, the full extent of Congress’s ability to subpoena and solicit information from the executive branch has never been defined, certainly not by the Supreme Court. Trump’s stubbornness has brought that question to the forefront of US politics again.

This fledging constitutional showdown might ultimately have to decide how much oversight the legislative branch is allowed to exercise over the president and his administration.