It’s been clear for a good while that the Trump Administration and the Democratic-controlled Congress are on a collision course, and the kinetic moment appears to be fast arriving. On Friday, Steven Mnuchin, the Treasury Secretary, refused to present his boss’s tax returns to the House Ways and Means Committee, despite being in receipt of a subpoena that ordered him to hand over the documents. Mnuchin’s decision came just forty-eight hours after Pat Cipollone, the White House counsel, sent a similarly defiant letter to Jerry Nadler, the head of the House Judiciary Committee, saying his office wouldn’t hand over documents that Nadler’s committee had demanded as part of its inquiry into whether President Trump obstructed justice during the Mueller investigation.

The legal arguments that Mnuchin and Cipollone put forward were neither subtle nor compelling. Ignoring the basic principle that it is for Congress to decide which matters it deems worthy of inspection, the two Trump appointees argued that the document requests lacked “a legitimate legislative purpose.” Mnuchin largely left things at that: his letter was one page long. But Cipollone’s twelve-page missive also slammed the investigation that Nadler is leading, referring to it as an effort to “harass political opponents” and to “pursue an unauthorized ‘do-over’ of exhaustive law enforcement investigations conducted by the Department of Justice.”

In addition to refusing Congress’s demands for documents, Trump’s legal team is moving to prevent key witnesses from testifying at hearings, or to place strict limits on what they say, by looking to assert executive privilege retroactively over issues covered in the Mueller report. An appearance by Robert Mueller himself, which had been rumored to be in the works for this week, didn’t take place. And it looks like Don McGahn, the former White House counsel, won’t be appearing next week, either. The Washington Post reported on Friday evening that “any hopes of . . . McGahn facing a congressional panel on Tuesday are slim, as the White House moves to block all current and former aides from cooperating with congressional inquiries.”

The Administration’s defiance isn’t confined to the White House and the Treasury Department, which oversees the Internal Revenue Service. Last week, the House Judiciary Committee voted to hold in contempt William Barr, the Attorney General, for his refusal to hand over a full version of the Mueller report. Far from rethinking his actions, or inactions, after that vote, Barr has been busy making a joke of it. On Wednesday, when he encountered Nancy Pelosi, the Speaker of the House, at an event on Capitol Hill, he asked her, “Madam Speaker, did you bring your handcuffs?” And, on Friday, Barr told Fox News that last week’s vote was simply part of a “political circus that’s being played out.”

To be sure, there is some public posturing going on. But underlying the theatrics is a deadly serious battle between an imperial President who is determined to treat the Congress as a subservient body rather than a coequal branch of government, and a Democratic Party that is trying to hold Trump accountable and satisfy the Party’s base, while also trying to avoid what some of its leaders, the House Speaker included, consider to be an impeachment trap that the President is trying to spring. At a meeting of the House Democratic caucus on Wednesday, Pelosi told her colleagues that rather than trying to impeach Trump they should concentrate on advancing their policy agenda, particularly health care, the Washington Post reported. “The point is that we need to show [voters] that we are doing all of these other things that they care about so much,” Pelosi said.

The most immediate destination for the House Democrats is almost certainly the federal courts, where they will ask judges to order the Administration to be more coöperative. “Given the Treasury Secretary’s failure to comply today, I am consulting with counsel on how best to enforce the subpoenas moving forward,” Richard Neal, the chairman of the Ways and Means Committee, said after he received Mnuchin’s letter. Given past rulings and the central role that the Constitution affords to Congress, many legal experts believe the courts will rule against the Administration in the dispute about handing over Trump’s tax returns, and in other cases, too. But the legal battle could well be a lengthy one, and it seems likely that the Administration will take at least some of the cases all the way to the Supreme Court, which now has a solid conservative majority. Given the prospect of long delays—and the blanket, taunting nature of the Administration’s defiance—pressure is growing on the Democratic leadership to seize the initiative. Referring to Pelosi’s cautious stance about impeachment, Marcia Fudge, a six-term Democratic congresswoman from Ohio, told the Washington Post at the end of the week, “We respect her leadership and we respect her strategic sense about how these things work, her political sense. But I think we’re all getting to a point where we know something more has to be done.”

Democratic leaders are all too aware of where things appear to be heading. Having commented in an interview earlier in the week that impeachment probably wasn’t going to happen, Nadler said something different when he was interviewed, on Thursday, by MSNBC’s Kasie Hunt. “Everything the President does now is making it more and more impossible to rule out impeachment,” Nadler said. “They are now taking the position that the Justice Department can’t hold the President accountable, since they say no President can be indicted, no matter what the evidence, as a matter of law. And now they are saying that Congress can’t hold the President accountable. That means the President is above the law, and that’s intolerable in a democratic society. We cannot permit that kind of arrogation of power.”