House Judiciary Chairman Jerrold Nadler’s subpoena of former White House counsel Don McGahn is “ridiculous,” President Donald Trump said Wednesday as Democrats continue their investigations of his business and political life.

The president also made clear that he and his legal team are dug in for what could be a protracted fight with House Democrats over their demands for witnesses to appear before several committees and requests for documents. Legal experts and political analysts already are predicting court battles and stall tactics that could last well into the 2020 election cycle.

“I say it’s enough. Get back to infrastructure, get back to cutting taxes, get back to lowering drug prices,” Trump told reporters, referring to issues both parties have said could be ripe for bipartisan legislation this year.

“The subpoena is ridiculous,” he said as he departed the White House for a speech on prescription drugs in Atlanta. “We’re fighting all the subpoenas.”

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On Monday, Nadler said “the moment for the White House to assert some privilege to prevent this testimony from being heard has long since passed.”

“I suspect that President Trump and his attorneys know this to be true as a matter of law and that this evening’s reports, if accurate, represent one more act of obstruction by an Administration desperate to prevent the public from talking about the President’s behavior,” the chairman said in a statement. “The committee’s subpoena stands. I look forward to Mr. McGahn’s testimony.”

Earlier Wednesday morning, the president again spent several hours firing off tweets attacking his foes and riling up his conservative base.

In one, he vowed to “head to the U.S. Supreme Court” if House Democrats even start impeachment proceedings.

Watch: Trump: ‘We’re fighting all the subpoenas’

The president appeared to be warning that he would pursue court action to block subpoenas summoning current and former White House aides to testify before several Democratic-controlled committees.

In another tweet, the president claimed “no ‘High Crimes and Misdemeanors,’” referring to the basis for any House impeachment process under the Constitution.

The Mueller Report, despite being written by Angry Democrats and Trump Haters, and with unlimited money behind it ($35,000,000), didn’t lay a glove on me. I DID NOTHING WRONG. If the partisan Dems ever tried to Impeach, I would first head to the U.S. Supreme Court. Not only……

— Donald J. Trump (@realDonaldTrump) April 24, 2019

…..are there no “High Crimes and Misdemeanors,” there are no Crimes by me at all. All of the Crimes were committed by Crooked Hillary, the Dems, the DNC and Dirty Cops – and we caught them in the act! We waited for Mueller and WON, so now the Dems look to Congress as last hope!

— Donald J. Trump (@realDonaldTrump) April 24, 2019

He also contended “there are no Crimes by me at all.” But Mueller did state, clearly, that Trump attempted to obstruct justice, and in some cases, the former FBI director said he found evidence in the president’s actions of obstruction.

The Mueller report did not take an official stance on whether Trump committed criminal-level obstruction, signaling in one section of the 448-page document that the question should be up to the House and Senate to answer.

[Will the White House or Trump’s lawyers block Don McGahn from testifying?]

Trying to blur those Constitution-based lines that the Mueller report spent some time explaining, the president also tweeted this: “We waited for Mueller and WON, so now the Dems look to Congress as last hope!”

That’s true for some House Democrats from the party’s most liberal wing who want impeachment proceedings to begin as soon as possible. But Speaker Nancy Pelosi of California and other top Democrats continue urging caution on impeachment.

A day after telling The Washington Post he opposes allowing his current and former White House officials to testify about the Mueller report findings, Trump wrote this in another post: “I allowed everyone to testify, including W.H. counsel. I didn’t have to do this, but now they want more.”

No Collusion, No Obstruction – there has NEVER been a President who has been more transparent. Millions of pages of documents were given to the Mueller Angry Dems, plus I allowed everyone to testify, including W.H. counsel. I didn’t have to do this, but now they want more…..

— Donald J. Trump (@realDonaldTrump) April 24, 2019

….Congress has no time to legislate, they only want to continue the Witch Hunt, which I have already won. They should start looking at The Criminals who are already very well known to all. This was a Rigged System – WE WILL DRAIN THE SWAMP!

— Donald J. Trump (@realDonaldTrump) April 24, 2019

A White House official told Roll Call on Monday that the Counsel’s Office inside the West Wing is exploring legal options to prevent officials like former White House Counsel Don McGahn from testifying. McGahn and others told Mueller they repeatedly ignored the president’s orders to impair or end Mueller’s probe, in part because they viewed the mandates as illegal.

“Executive privilege is on the table. That’s his right,” White House counselor Kellyanne Conway told reporters Wednesday outside the West Wing.

But some legal experts are warning the White House they likely would lose a legal fight.

“The ship has sailed. As a legal matter it is quite clear: He waived his legal privilege when he agreed to let his aides … sit down with the Special Counsel,” Jessica Roth, a former federal prosecutor who now teaches law at Cardozo School of Law, told CNN Wednesday. “The court could find that these communications constituted the president’s attempt to construct justice. And by that standard, they’re not covered by the privilege.”

Meanwhile, “I assume” Mueller “checked my taxes … and my financials,” Trump said Wednesday as House Democrats and the party’s 2020 presidential candidates continue to press for the release of his tax returns.

The president, despite refusing for four years to release his returns, said his “financials” are “great.”

The Mueller report, however, did not focus on the president’s tax returns or financial records.