Former Trump campaign chairman Paul Manafort in Alexandria on March 8. (Shawn Thew/EPA-EFE/Shutterstock)

Harry Litman practices law at the firm Constantine Cannon and teaches constitutional law at the University of California at San Diego. He served as deputy assistant attorney general in the Justice Department from 1993 to 1998 and U.S. attorney for the Western District of Pennsylvania from 1998 to 2001.

The most enduring mystery to date in special counsel Robert S. Mueller III’s inquiry has been former Trump campaign manager Paul Manafort’s obdurate refusal to cooperate with the investigation. Manafort has a reputation as a swashbuckling gambler, but he has been playing odds in the biggest game of his life that are not just long but prohibitive. A new report that the president’s now-former lawyer once discussed pardoning Manafort may finally explain why the latter has kept quiet — even though that bet is still incredibly risky.

Manafort’s refusal to cooperate can’t be driven by a rational calculation that he has any reasonable chance of escaping conviction, multimillion-dollar legal fees and a prison sentence that will result in years behind bars.

The indictments against him lay out an overwhelming case of money laundering in particular. The meticulously gathered evidence will be as clear for the jury as a laundry detergent commercial: The jury will see the dirty money go in and the clean money come out. To the extent there had been a small risk, inherent in paper-driven chases, that the jury could become bored at the accounting presentation and tune out, Mueller now has a narrator for the trial in Manafort’s co-conspirator Rick Gates.

As the federal judge overseeing just one of the two federal trials Manafort now faces wrote, “Given the nature of the charges against the defendant and the apparent weight of the evidence against him, [Manafort] faces the very real possibility of spending the rest of his life in prison.”

And U.S. District Judge T.S. Ellis III was referring only to one of the two substantial cases pending against Manafort, who is facing 30 criminal charges in two jurisdictions; his trial dates have been set at July 10 in Virginia and Sept. 17 in Washington. (Manafort declined an offer to consolidate the charges in the District.)

In fact, no credible defense lawyer would advise Manafort that he can win the case. And if by some miracle he secures a mistrial, the government will retry the charges — the stakes are too high.

Enter the new revelation: The New York Times reported that last summer John Dowd, Trump’s lead defense lawyer until his resignation last week, broached the subject of a possible pardon with Reginald Brown, Manafort’s lawyer at the time, just before Manafort was initially indicted.

So the report provides what, at least based on the available evidence, is the best hypothesis for Manafort’s intransigence. Manafort believes he has a get-out-of-jail-free card, so long as he keeps quiet and absorbs the costs of trial.

Note the first corollary here, which is the likelihood that both Trump and Manafort understand that Manafort has knowledge that could bury the president. Otherwise Trump would not hazard, and Manafort would not credit, the offer. We know Manafort and Trump continued to communicate after Manafort was chased from the campaign and that Trump himself reportedly confided to others that Manafort could inculpate him.

That said, the Times story does not definitively solve the Manafort mystery. First, Dowd’s reported overture, particularly if done with the president’s knowledge or consent, could have constituted a conspiracy to obstruct justice, a separate impeachable offense. That presumably is why the story includes a categorical denial from Dowd that he ever discussed pardons for the president’s former advisers with lawyers. For Dowd, the conduct would be putting his license at risk.

Second, Manafort surely recognizes that he can’t fully count on Trump, both because the president is a habitual liar and because the political dynamic is subject to such extreme and violent turns. (Of course, under this hypothesis, Manafort retains the valuable insurance policy of spilling the goods if Trump double-crosses him, leaving both huge losers in a real-life prisoners dilemma.)

Third, Manafort could still be required to testify after any pardon, when he would no longer be in federal jeopardy. Undoubtedly, the plan would be for him to deny assurances of a pardon from Trump. Still, were Mueller to catch him in a lie, the special counsel would surely come down on him.

Finally, it is likely that in the event of a pardon for federal crimes, which is all Trump can provide, some state attorneys general, such as New York’s Eric T. Schneiderman, would prosecute Manafort for financial crimes under their potent state statutes.

Still, the report of a dangled possible pardon moves the odds of Manafort holding out from stratospheric to simply long. Too long for his co-defendant Michael Flynn, the former national security adviser who opted for the safer course, but maybe just attractive enough for a high-stakes gambler such as Manafort. And, of course, part of Manafort’s calculations may be that Trump could sweeten the pot if, as Trump fears, Manafort is sitting on information against the president that no one else has.

Gentlemen, place your bets.