Even as President Donald Trump’s lawyers negotiate a possible voluntary interview with special counsel Robert Mueller, a subpoena showdown in the Russia collusion investigation is inevitable, former federal prosecutor Andrew McCarthy said Thursday.

McCarthy, who prosecuted terrorism cases during the 1990s in New York, said on “The Laura Ingraham Show” that chances are “pretty high” for negotiations to break down at some point and that Mueller will seek a subpoena in court to question Trump under oath about Russian interference in the 2016 presidential campaign.

McCarthy said he bases that judgment on how aggressive Mueller’s team has been so far. He pointed to the criminal trial of Trump’s former campaign chairman, Paul Manafort. Prosecutors in that case “squeezed” Manafort’s accountant and one of his lawyers to testify about the alleged tax and bank fraud charges, he noted.

“When you’re playing the game at those kinds of stakes, I can’t see these guys passing up a chance of a subpoena, and you know, figuring, ‘We’ll litigate it. If we lose, we lose,'” he said. “But I can’t seem them just saying, ‘Nah, never mind, we won’t do it.'”

Mueller’s team has been trying for months to arrange an interview with Trump about his knowledge of Russia’s attempts to influence the election and — according to what many analysts have speculated — whether the president has attempted to obstruct the investigation.

Trump’s lawyers have offered to make the president available for a relatively short interview, with some questions in writing, and limited questions involving obstruction.

McCarthy said the issue has been incorrectly framed.

“The burden here is on the wrong side. Everybody is looking to whether the president will agree to, you know, some procedural terms for this interview,” he said. “And it seems to me that, having been a prosecutor for a long time, you don’t just get to interview the president because it would be interesting.”

McCarthy said that because of the unique demands of the presidency, Mueller should be required to demonstrate that there is a serious crime that the president has knowledge of, and that there is no other way to get the information he seeks.

“If he can’t satisfy those two things, I don’t even know why we’re talking about whether he should sit down with him or not,” he said.

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Unlike an ordinary criminal investigation, McCarthy said, the governance of the country outweighs traditional interests in investigative secrecy.

“Put your cards on the table, Show us what you got,” he said. “And if there’s a serious crime that the president’s implicated in, all right, then we should talk about whether it’s by subpoena or how he sits down. Have the interview. But first, we need something from this prosecutor.”

“If the president decides he shouldn’t be subpoenaed, who is Mueller to countermand that?”

If it does come to a legal fight, McCarthy said, Trump has a strong constitutional argument. The Constitution vests all executive power in the president. McCarthy said that means everyone in the executive branch works for him and, ultimately, answers to him.

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Although many people treat Mueller like he is an independent prosecutor, he actually works for the Department of Justice (DOJ) and is below Trump in the chain of command, McCarthy said.

“Mueller is an inferior executive officer. The president is the chief executive,” he said. “If the president decides he shouldn’t be subpoenaed, who is Mueller to countermand that?”

Interview or no, McCarthy said, Mueller likely will write a report at the conclusion of his investigation that does not allege Trump committed any crime but eviscerates him nonetheless.

“It’s gonna be an ugly report, I think,” he said.

(photo credit, article image: Donald Trump at Aston, PA, CC BY 2.0, by Michael Vadon)