An attorney for President Trump stressed Sunday that the president's legal team would contest any effort to force the president to testify in front of a grand jury during the special counsel's Russia probe but downplayed the idea that Mr. Trump could pardon himself.

Rudy Giuliani, in a series of television interviews, emphasized one of the main arguments in a newly unveiled letter sent by Mr. Trump's lawyers to special counsel Robert Mueller back in January: that a president can't be given a grand jury subpoena as part of the investigation into foreign meddling in the 2016 election.

But he distanced himself from one of their bolder arguments in the letter, which was first reported Saturday by The New York Times, that a president could not have committed obstruction of justice because he has authority to "if he wished, terminate the inquiry, or even exercise his power to pardon."

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"Pardoning himself would be unthinkable and probably lead to immediate impeachment," Giuliani told NBC's "Meet the Press." ″And he has no need to do it, he's done nothing wrong."

The former New York City mayor, who was not on the legal team when the letter was written, added that Trump "probably does" have the power to pardon himself, an assertion challenged by legal scholars, but says the president's legal team hasn't discussed that option, which many observers believe could plunge the nation into a constitutional crisis.

"I think the political ramifications would be tough," Giuliani told ABC's "This Week." ″Pardoning other people is one thing, pardoning yourself is tough."

Mr. Trump has issued two unrelated pardons in recent days and discussed others, a move that has been interpreted as a possible signal to allies ensnared in the Russia probe.

The letter is dated Jan. 29 and addressed to Mueller from John Dowd, a Trump lawyer who has since resigned from the legal team. Mueller has requested an interview with the president to determine whether he had criminal intent to obstruct the investigation into his associates' possible links to Russia's election interference.

Giuliani said Sunday that a decision about an interview would not be made until after Mr. Trump's summit with North Korean leader Kim Jong Un on June 12 in Singapore, and he cast doubt that it would occur at all.

"I mean, we're leaning toward not," Giuliani told ABC. "But look, if they can convince us that it will be brief, it would be to the point, there were five or six points they have to clarify, and with that, we can get this -- this long nightmare for the -- for the American public over."

Mr. Trump's legal team has long pushed the special counsel to narrow the scope of its interview. Giuliani also suggested that Mr. Trump's lawyers had been incorrect when they denied that the president was involved with the letter that offered an explanation for Donald Trump Jr.'s 2016 Trump Tower meeting with Russians who offered damaging information on Democrat Hillary Clinton.

"This is the reason you don't let the president testify," Giuliani told ABC. "Our recollection keeps changing, or we're not even asked a question and somebody makes an assumption."

If Mr. Trump does not consent to an interview, Mueller will have to decide whether to go forward with a historic grand jury subpoena. His team raised the possibility in March of subpoenaing the president, but it is not clear if it is still under active consideration.

A court battle is likely if Mr. Trump's team argues that the president can't be forced to answer questions or be charged with obstruction of justice. President Bill Clinton was charged with obstruction in 1998 by the House of Representatives as part of his impeachment trial. And one of the articles of impeachment prepared against President Richard Nixon in 1974 was for obstruction.

Giuliani suggested Sunday that, despite the president's broad powers, a theoretical charge of obstruction may be possible in some cases. Topics of Mueller's obstruction investigation include the firings of FBI director James Comey and former national security adviser Michael Flynn, as well as Mr. Trump's reaction to Attorney General Jeff Sessions' recusal from the Russia investigation.

In addition to the legal battles, Mr. Trump's team and allies have waged a public relations campaign against Mueller and the Justice Department to discredit the investigation and soften the impact of the special counsel's potential findings. Giuliani said last week that the special counsel probe may be an "entirely illegitimate investigation" and need to be curtailed because, in his estimation, it was based on inappropriately obtained information from an informant and Comey's memos.

In reality, the FBI began a counterintelligence investigation in July 2016 to determine if Trump campaign associates were coordinating with Russia to tip the election. The investigation was opened after the hacking of Democratic emails that intelligence officials later formally attributed to Russia.

Mr. Trump's team has asked for a briefing about the informant, but Giuliani said Sunday that the president would not order the Justice Department to comply because it would negatively affect public opinion. But he continued to cast doubt on the special counsel's eventual findings, suggesting that Trump has already offered explanations for the matters being investigated and that the special counsel was biased against the president.

"For every one of these things he did, we can write out five reasons why he did it," Giuliani said. "If four of them are completely innocent and one of them is your assumption that it's a guilty motive, which (Trump) would deny, you can't possibly prosecute him."

The special counsel's office did not respond to a request for comment.

Mr. Trump, who was spending a rainy Washington weekend at Camp David, also unleashed a new attack on the Justice Department, which he has repeatedly painted as corrupt and biased against him.

"As only one of two people left who could become President, why wouldn't the FBI or Department of 'Justice' have told me that they were secretly investigating Paul Manafort (on charges that were 10 years old and had been previously dropped) during my campaign? Should have told me!" Mr. Trump tweeted.

....Paul Manafort came into the campaign very late and was with us for a short period of time (he represented Ronald Reagan, Bob Dole & many others over the years), but we should have been told that Comey and the boys were doing a number on him, and he wouldn’t have been hired! — Donald J. Trump (@realDonaldTrump) June 3, 2018

Manafort, who was Mr. Trump's campaign chairman, faces charges of acting as an unregistered foreign agent and money-laundering conspiracy and also two false-statement charges related to information he shared with the Justice Department about his Ukrainian political work. Mr. Trump has argued that the claims predate Manafort's involvement with his Republican campaign. The FBI has not said it told the campaign about the investigation, though the bureau did provide a routine briefing for the campaign about foreign counterintelligence threats.