President Trump on Monday asserted an “absolute right” to pardon himself of any federal crimes but said he has no reason to do so because he has not engaged in any wrongdoing.

“As has been stated by numerous legal scholars, I have the absolute right to PARDON myself, but why would I do that when I have done nothing wrong?” Trump wrote on Twitter.

In a subsequent tweet Monday, Trump also claimed that the appointment of special counsel Robert S. Mueller III to investigate Russian interference in the 2016 election had been “totally UNCONSTITUTIONAL!”

“Despite that, we play the game because I, unlike the Democrats, have done nothing wrong!” Trump said.

Trump’s assessment of his pardon powers echoed that of his attorney, Rudolph W. Giuliani, who offered an expansive view of the president’s executive powers during interviews Sunday, arguing that Trump probably has the ability to pardon himself.

“He probably does,” Giuliani said Sunday, when asked on ABC News’s “This Week” whether Trump has the ability to pardon himself. “He has no intention of pardoning himself, but he probably — not to say he can’t.”

Giuliani’s comments came less than 24 hours after the revelation Saturday that the president’s legal team argued in a confidential January memo to Mueller that Trump could not have obstructed an FBI probe into Russian interference in the 2016 election because, as president, he has total control over all federal investigations.

In his tweets Monday, Trump again lashed out at Mueller’s probe, calling it a “never ending Witch Hunt,” asserting that it was led by “13 Angry and Conflicted Democrats (& others)” and predicting that it would continue through the midterm elections.

Mueller is a Republican, as is Deputy Attorney General Rod J. Rosenstein, a Trump appointee overseeing Mueller’s investigation.

Legal scholars differ on the issue of whether the president can pardon himself — and even some Republicans question the reading of the law by Trump’s legal team.

Senate Judiciary Committee Chairman Charles E. Grassley (R-Iowa) suggested Monday that Trump should hire a new lawyer if he is being told he can pardon himself.

“If I were president of the United States, and I had a lawyer that told me I could pardon myself, I think I would hire a new lawyer,” Grassley told CNN.

The question of whether a president can self-pardon has long been a “parlor game” among scholars, said Jonathan Turley, a constitutional law professor at George Washington University Law School.

There is no precedent for it and, thus, no case law. Turley said he believes a president can pardon himself — but added that it would not protect a president from impeachment.

“A president cannot pardon out of an impeachment,” Turley said. Congress, he said, “can use his pardon as an abuse of his office.”

Ethan Leib, a professor at Fordham Law School, said he believes a president can’t self-pardon because that violates the oath of office — in which the president swears to “faithfully execute” his duties — and the stipulation in Article II of the Constitution that the president “shall take care that the laws be faithfully executed.”

“The Constitution is clearly prohibiting the president from engaging in self-dealing,” Leib said.

Trump did not say in his tweets why he believes the Mueller probe is unconstitutional.

Late last month, Steven Calabresi, one of the founders of the conservative Federalist Society, argued in a guest editorial in the Wall Street Journal that Mueller cannot oversee such a broad investigation because he was not confirmed by the Senate.

Calabresi asserted that under the appointments clause of the Constitution, an official overseeing the probe would be a “principal officer” and would have to be someone who was appointed by the president and confirmed by the Senate.

Among those pushing back on that view Monday were Rep. Jerrold Nadler (N.Y.), the ranking Democrat on the House Judiciary Committee.

“The appointment of Special Counsel Mueller is clearly constitutional,” Nadler said in a statement in which he referenced a top former Trump campaign aide who has been indicted by Mueller. “We know this, in part because Paul Manafort — the president’s old campaign manager — tried the same desperate argument in federal court last month. The court rejected that motion, and Manafort will rightly face trial for his alleged crimes in due course.”

With Trump going on Twitter again to undermine the Mueller probe, Senate Minority Leader Charles E. Schumer (D-N.Y.) sought to bolster its legitimacy.

In a tweet directed at Trump on Monday, Schumer wrote: “Special Counsel Mueller’s investigation has either indicted or secured guilty pleas from 19 people and three companies. Five of these people, including three former Trump aides, have already pleaded guilty.”

Other Democrats, including Sen. Jeanne Shaheen (N.H.), also took aim at Trump in response to his assertions on Twitter.

“All the tweeting in the world will not change the fact that the President is not above the law,” Shaheen said in a tweet of her own.

Trump’s tweet about his pardon power comes as he has issued a string of pardons of others, most recently conservative commentator Dinesh D’Souza.

As he pardoned D’Souza last week for a campaign finance law violation, Trump also said he was weighing commuting the prison sentence of former Illinois governor Rod Blagojevich (D) as well as granting a pardon to Martha Stewart, the television personality and lifestyle mogul, arguing that they and D’Souza had been unfairly treated by the justice system.

Many have seen Trump’s actions as a signal to personal attorney Michael Cohen, former national security adviser Michael Flynn and others ensnared in Trump-related investigations that they, too, could be spared punishment in the future.

Trump also used Twitter on Monday to mark his 500th day in office. In an earlier tweet, he said he had “accomplished a lot — many believe more than any President in his first 500 days.” The president ticked off accomplishments, including “Best Economy & Jobs EVER.”

Joel Achenbach, Devlin Barrett and Ashley Parker contributed to this report.