Former national security adviser Michael Flynn wants immunity before he testifies to Congress, but the type of deal he’s seeking is rarely granted — in large part because of the Iran-contra scandal of the 1980s.

Flynn’s lawyer, Robert Kelner, has reached out to the Senate Intelligence Committee in the hopes of getting a wide-ranging grant of immunity in exchange for his client’s testimony to lawmakers, but an official familiar with the discussion says the idea of immunity is “off the table,” particularly given the early stage of the congressional investigations involving Flynn.

Two congressional committees and the FBI are probing whether any associates of President Trump coordinated with agents of Russia as that country meddled in the U.S. presidential election last year. Flynn is a major figure in that investigation, because his conversations with the Russian ambassador to the United States ultimately led to his ouster from the White House.

“General Flynn certainly has a story to tell, and he very much wants to tell it, should the circumstances permit,” Kelner said Thursday. The overture is notable in part because during the presidential campaign, Flynn said that people who are given immunity “probably committed a crime.”

On Friday morning, the president tweeted: “Mike Flynn should ask for immunity in that this is a witch hunt (excuse for big election loss), by media & Dems, of historic proportion!”

View Graphic Team Trump’s ties to Russian interests

White House press secretary Sean Spicer said the president was not trying to suggest to the Justice Department or the investigating committees that Flynn should receive immunity, but rather that Flynn and others should talk to Congress, with legal precautions.

“We’ve actually encouraged people to go talk to the House and Senate intelligence committees and the appropriate investigators so that they can continue to get to the bottom of this,” Spicer said.

But procedural rules and political realities will make it difficult for Flynn to get immunity. Democrats, in particular, sounded wary of giving Flynn a pass for any potential crimes.

Adam B. Schiff (Calif.), the ranking Democrat on the House Intelligence Committee, on Friday called it “a grave and momentous step for a former national security adviser to the president of the United States to ask for immunity from prosecution.”

Schiff said there will be discussions between the committees and the Justice Department about Flynn’s offer, but cautioned there was still “much work and many more witnesses and documents to obtain before any immunity request from any witness can be considered.”

Congress has the authority to grant a limited type of immunity, called derivative use immunity, through which a witness can be compelled to testify, on the condition that their statements to Congress will not be used by prosecutors to gather evidence for a future criminal prosecution.

Lawyer William W. Taylor said grants of congressional immunity “are rare, and there are rules and regulations about consulting with the attorney general before you give somebody immunity. But if there’s a prosecution or a grand jury looking into this, obviously Mr. Flynn would be happy to be immunized by anybody.”

(Video: Reuters)

Grants of such immunity must also involve discussions with senior Justice Department officials, but even that type of limited immunity is problematic, in large part because of the case of Oliver North.

North, a central figure in the 1980s Iran-contra affair, was granted limited immunity to testify to Congress at length about his role in the covert arms-for-hostages deal with Iran that the Reagan administration had sought. The hearings in 1987 were watched by millions of Americans.

North was later prosecuted and convicted of crimes for ordering the destruction of documents and obstructing a congressional inquiry, but an appeals court threw out the conviction. The court found that while prosecutors were careful not to use his testimony to gather evidence, witnesses in the criminal case had seen or heard about his testimony, and that exposure tainted the conviction.

Since the North case, prosecutors generally regard it as difficult, if not impossible, to prosecute someone who has been granted limited congressional immunity.

The North case was “a warning that if somebody gets immunity from Congress, you’re going to have a heck of a time persuading a court you can prosecute them,’’ Taylor said.