President Trump is in an all-out war against the House’s investigations. He and his allies are attempting to block more than 20. (Jabin Botsford/The Washington Post)

President Trump and his allies are working to block more than 20 separate investigations by Democrats into his actions as president, his personal finances and his administration’s policies, according to a Washington Post analysis, amounting to what many experts call the most expansive White House obstruction effort in decades.

Trump’s noncooperation strategy has shifted from partial resistance to all-out war as he faces mounting inquiries from the Democratic-controlled House — a strategy that many legal and congressional experts fear could undermine the institutional power of Congress for years to come. All told, House Democrats say the Trump administration has failed to respond to or comply with at least 79 requests for documents or other information.

The president is blocking aides from testifying, refusing entire document requests from some committees, filing lawsuits against corporations to bar them from responding to subpoenas and asserting executive privilege to keep information about the special counsel’s Russia investigation from public view. One such case will come to a head in court on Tuesday, when a federal judge is expected to rule on whether Trump can quash a House Oversight Committee subpoena demanding financial records from his personal accounting firm.

The administration also faces another subpoena deadline Friday for Trump’s tax returns following the administration’s move to refuse access to them. Trump signaled Saturday that he will continue to refuse disclosure of his tax returns because he says he is being audited by the IRS, though that would not preclude such a release. He also suggested that Democratic attempts to force their release would help him win a second term.

“I won the 2016 Election partially based on no Tax Returns while I am under audit (which I still am), and the voters didn’t care,” Trump tweeted. “Now the Radical Left Democrats want to again re-litigate this matter. Make it a part of the 2020 Election!”

Kerry W. Kircher, who served as House counsel for the last GOP majority, said the standoff marks “a complete breakdown and complete obstruction of Congress’s role.”

“If the court signs off on this stuff, then we’ll have an imperial presidency,” Kircher said, adding: “We’ll have a presidency that will be largely unchecked.” 

Trump’s block-everything strategy stands in contrast to the White House approach to special counsel Robert S. Mueller III’s investigation into Russian interference in the 2016 election, when Trump allowed his aides to speak to the special counsel and even turned over documents. Now, the White House is refusing to give an inch on investigations pertaining to the president.

Trump and his allies view the array of probes by Democrats as overreaching political attacks aimed at undermining his presidency and his reelection effort.

“There are rules and norms governing congressional oversight of the executive branch, and the Democrats simply refuse to abide by them,” said deputy White House press secretary Steven Groves. “Democrats are demanding documents they know they have no legal right to see — including confidential communications between the president and foreign leaders and grand jury information that cannot be disclosed under the law. This White House will not and cannot comply with unlawful demands made by increasingly unhinged and politically-motivated Democrats.”

Republicans on Capitol Hill also defend Trump’s decision to resist congressional inquiries, with Sen. Lindsey O. Graham (R-S.C.) calling the investigations the result of a political party still embittered about losing the White House in 2016. 

“If I were Trump, I’d protect my family, and I’d protect my interests of the presidency and fight it out in court,” Graham said. “Oversight’s one thing. Revenge is another.” 

But Democrats say their probes are part of legitimate congressional oversight — spanning issues such as the hurricane-recovery effort in Puerto Rico, the administration’s abandoned family separation policy at the border and Trump’s attempt to build a border wall without congressional approval.

Meanwhile, Democrats are also examining dozens of actions involving administration policies rather than Trump himself. The Energy and Commerce Committee, for instance, has sent out more than 30 oversight requests to agencies that are responsible for health, environment and consumer protection issues, with varying levels of response.

The Post analysis of Democratic inquiries and other records identified more than 20 investigations directly connected to Trump, his family or the White House that have been met with partial or complete stonewalling by the administration. 

“I think it is unprecedented in its vehement concealment and noncompliance with basic constitutional duties,” Sen. Richard Blumenthal (D-Conn.) said of the administration’s broader strategy to not respond to investigations from the Hill. “Congress has some undeniable powers under the Constitution, and one of them is oversight.”

Congress and the executive branch have always had a tense relationship, especially when the opposition party controls the House or Senate. When President Barack Obama was in the White House, House Republicans held Attorney General Eric H. Holder Jr. in contempt of Congress for refusing to hand over documents pertaining to the “Fast and Furious” gunrunning case in the Justice Department.

The Obama administration begrudgingly cooperated with several Republican investigations that the Democratic president’s allies viewed as politically motivated. The House Oversight Committee conducted private interviews with several IRS officials amid allegations that the tax agency was targeting tea party groups for scrutiny. And some of Obama’s top White House aides sat for closed-door depositions as part of the GOP’s years-long Benghazi investigation. 

Trump’s approach toward House Democrats’ investigations, experts say, is different because of the sheer number of investigations he is choosing to ignore or actively resist.

In the past week alone, Trump and the White House blocked three major inquiries — rebuffing requests for his tax returns, refusing to turn over an unredacted version of Mueller’s final report on Russian interference and barring former White House counsel Donald McGahn from responding to a Hill subpoena. 

Congress has had the power to request any individual’s tax returns since 1924, when the Teapot Dome scandal set off a flurry of Hill investigations amid allegations of bribery and self-dealing. 

The law says the treasury secretary “shall furnish” tax returns to Congress upon request. But Treasury Secretary Steven Mnuchin on Tuesday declined a request under the law from House Ways and Means Committee Chairman Richard E. Neal (D-Mass.), saying that the demand served no “legitimate legislative purpose.” House investigators responded on Friday with a subpoena as they ready a lawsuit aimed at forcing compliance with the request.

The same day, Trump officials barred McGahn from turning over subpoenaed information related to Mueller’s investigation, potentially opening him up to legal peril and a contempt of Congress charge. McGahn was a central witness in several of 10 instances of potential obstruction of justice identified in the Mueller report. 

McGahn may not be the only former White House aide who will be targeted by Democrats. House Democrats have a long list of former Trump officials they want to speak with, but Trump has told aides he does not want anyone to cooperate with congressional investigators.

Last Wednesday, the president also asserted executive privilege for the first time over the entire Mueller report, though much of it has already been released to the public. Mueller did not establish criminal conspiracy between the Trump campaign and Russia, but he declined to reach a decision on whether Trump obstructed justice in the investigation. Barr concluded that the evidence did not support obstruction charges.

Democrats say they need to view the underlying evidence gathered over the course of nearly two years by Mueller to reach their own conclusion on whether Trump may have obstructed justice in the probe. A House committee voted Wednesday to hold Barr in contempt of Congress for refusing to turn over the information.

“Now that the president has been fully and completely exonerated after three years of FBI and DOJ investigation, Democrats are concocting new conspiracy theories,” said Kayleigh McEnany, national press secretary for the Trump campaign. “The American people want legislating, not investigating, but Democrats continue their fanatical quest to overthrow the legitimate results of an election. Their baseless, fact-free investigations are a disgrace.” 

Trump’s personal and business lawyers have also sued the House Oversight Committee and his former accounting firm, Mazars, to block a subpoena. The inquiry gained steam after Trump’s former attorney Michael Cohen alleged in a February hearing that Trump inflated his wealth for insurance purposes but deflated it to avoid taxes.

Former House counsels of both political parties question the logic of the lawsuit. Trump’s lawyers cite a court precedent from 1880 that suggests Congress cannot investigate individuals, but many lawyers note that ruling was overturned in the 1920s and has not been followed in nearly 100 years.

Trump’s lawyers are also suing Deutsche Bank, a Trump lender, and Capital One, his private bank, to stop them from cooperating with the House Financial Services and Intelligence committees on a probe involving alleged Russian money laundering. In a joint statement, Trump lawyers William S. Consovoy, Patrick Strawbridge and Marc Mukasey called the subpoenas “unlawful and illegitimate.” 

“Every citizen should be concerned about this sweeping, lawless, invasion of privacy,” they said. “We look forward to vindicating our clients’ rights in this matter.”

Trump is also defending himself against plaintiffs in two lawsuits alleging that his company violates the Constitution by doing business with foreign governments. The Constitution bars any government official from receiving foreign payments known as “emoluments” while in office. Since Trump still has a vested interest in his company, Trump critics argue his foreign hotel patrons are boosting his bottom line. 

In a case brought in Maryland by the attorneys general of D.C. and Maryland, Justice Department lawyers representing the president have succeeded in temporarily blocking subpoenas for financial records and other documents related to the Trump International Hotel in Washington. A second case, brought by 200 congressional Democrats, extends beyond the hotel and provides a potential new avenue for investigators to gain access to a broader array of Trump’s closely held finances

On Capitol Hill, multiple committees are also investigating whether the lease for Trump’s D.C. hotel, which operates in the federally owned Old Post Office Pavilion, violates the Constitution. The committees have tried to circumvent Trump officials to get information from the General Services Administration, which oversees leases of government property, but they say they have only received partial responses.

The White House has also refused to provide documents demanded by the House Oversight Committee involving its security clearance process. In April, the White House instructed former personnel security director Carl Kline not to appear for a subpoenaed deposition, although Kline later agreed to answer broad questions.  

Other pending Democratic investigations focus on Trump administration policies.

The administration has resisted providing several pieces of information involving immigration issues. One request from the House Homeland Security Committee on Jan. 4 — which included questions about the border, asylum seekers and the treatment of children in federal custody — was only partially answered, according to a committee spokesman. 

Others, including requests for information about a proposal to bus migrants to the districts of political adversaries, have either been ignored or not fully answered.

The White House has also rebuffed House Judiciary Committee inquiries into the legal basis of Trump’s emergency declaration on the southern border, which the president issued in February to secure money for a wall that Congress declined to provide.

Five House committees wrote to the White House, the Justice Department, and Health and Human Services in April demanding documents regarding why the administration decided to no longer defend the Affordable Care Act in court. They have received no substantive response. 

The White House also declined to provide information involving private communications between Trump and Russian President Vladi­mir Putin, calling the request from a trio of House committees “sweeping” and saying that foreign policy was solely in the purview of the executive branch.

Tom Campbell, a former Republican congressman and a professor at Chapman University, said that while Democrats share some of the blame in the breakdown of the system, their inquiries of Trump are justifiable.

“These are perfectly legitimate oversight functions,” Campbell said. “No system works — even one as brilliantly constructed as the United States Constitution — works without good faith. . . . When good faith falls apart, the ability for the Constitution to work is compromised.”

Toluse Olorunnipa and Jonathan O’Connell contributed to this report.