Trump says he has 'absolute right' to pardon himself, calls special counsel 'unconstitutional'

President Donald Trump on Monday declared that he has the authority to pardon himself in any Russia investigation.

This question of pardoning has come up over the past few months as special counsel Robert Mueller and his team continue to investigate Russian interference in the 2016 U.S. election.

"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? In the meantime, the never ending Witch Hunt, led by 13 very Angry and Conflicted Democrats (& others) continues into the mid-terms!" he wrote on Twitter.

At Monday's White House briefing, press secretary Sarah Sanders, when asked repeatedly asked to explain the president's view on pardoning himself, answered repeatedly by saying, "Thankfully, the president hasn’t done anything wrong and wouldn't have any need for a pardon."

"Certainly, no one is above the law," Sanders later added after being asked multiple times if the president himself above the law.

Rudy Giuliani told ABC News chief anchor George Stephanopoulos on Sunday that the president "probably does" have the ability to pardon himself.

"He has no intention of pardoning himself," said Giuliani, a former mayor of New York City and Trump's lead attorney in negotiating an end to Mueller's ongoing investigation. "[It is a] really interesting constitutional argument: 'Can the president pardon himself?'"

Giuliani added, "I think the political ramifications of that would be tough. Pardoning other people is one thing. Pardoning yourself is another. Other presidents have pardoned people in circumstances like this, both in their administration and sometimes the next president even of a different party will come along and pardon."

Trump also tweeted about the special counsel investigation, saying that it was "unconstitutional."

"The appointment of the Special Councel [sic] is totally UNCONSTITUTIONAL! Despite that, we play the game because I, unlike the Democrats, have done nothing wrong!" he posted.

The argument that Mueller's appointment by Deputy Attorney General Rod Rosenstein is unconstitutional has found some traction within conservative media circles. Radio host Mark Levin reasoned late last month that because attorneys on Mueller’s team recently identified themselves in Virginia federal court as "Special Assistant US Attorneys" then Mueller should in turn be classified as a "roving U.S. attorney."

"Rosenstein usurped the authority of the president of the United States to nominate whoever he wants as a prosecutor," Levin said.

Levin said the status of Mueller's team violates the Appointments Clause under the Constitution and publicly urged defendants called on to testify by the special counsel to challenge his authority in court.

Giuliani has previously argued that the special counsel's investigation is "illegitimate." But the president's accusation is the newest escalation in the Trump legal team's effort to discredit Mueller's probe.

Sanders said that "scholars have raised a number of questions about the legality of the special counsel process."

Separately, one White House official provided to ABC News an outline of arguments by scholars that included Stephen Calabresi, the Clayton J. and Henry R. Barber Professor of Law at Northwestern University Pritzker School of Law and Douglas Kmiec, a Pepperdine University professor of constitutional law.

Kmiec has argued Mueller's actions have exercised a scope of authority comparable to a principal officer or Cabinet member, positions that would be subject to approval and confirmation by the Senate after being nominated.

“The only time you need a special counsel is when the Department of Justice is incapable of performing its job because the highest levels of the Department of Justice are recused with regards to a criminal matter,” Kmiec said. “What is the basis for appointing a special counsel when there is no real evidence?”

Trump's tweet prompted a backlash from Capitol Hill from Republicans and Democrats concerned about the potential use of the pardon power.

"President Trump has asserted that he has the ‘absolute’ right to pardon himself, and that the appointment of the Special Counsel is ‘unconstitutional.’ He thinks that, because he is the President, his actions cannot be an obstruction of justice," Rep. Jerry Nadler, D-New York, the top Democrat on the House Judiciary Committee, said in a statement. "His lawyers think that he can ignore a subpoena from a federal grand jury, and threaten the Special Counsel accordingly."

“But President Trump is wrong," Nadler said.

Sen. Chuck Grassley, an Iowa Republican, the chairman of the Senate Judiciary Committee, told CNN, “If I were POTUS and I had a lawyer tell me I could pardon myself, I think I’d hire a new lawyer.”

"I’m not a constitutional scholar," Sen. Ron Johnson, a Wisconsin Republican, told ABC.

"I haven’t looked at the law," Sen. Marco Rubio, a Florida Republican – who has a law degree – said.

"There are smarter people than me to ask," a GOP Sen. Lindsey Graham from South Carolina – and an Air Force lawyer – said.

"I’m not acting like a judge right now," said Sen. John Cornyn -- a former Texas Supreme Court justice.

Sen. John Kennedy, A Louisiana Republican, said there's only one place for this question to play out.

"Ultimately an issue like that would land in the lap of the United States Supreme Court. Let's hope we don't get there," he said.

While Graham wouldn't say whether he agreed that the president could pardon himself he said Trump shouldn't try.

"Politically, it'd be a terrible idea. Legally, I don't know," he said. "I do know this: One of the limits of the president's authority is politics. And I think the politics would be very bad."

ABC News' Ali Rogin and Benjamin Siegel contributed to this report.