He’s been making impressive deals for decades, but the most important deal Donald Trump will ever make is with Vice President Mike Pence—for a pardon. And not just any pardon, but the broad-brush, get-out-of-jail-free kind that the newly installed President Gerald Ford granted to Richard Nixon even before Nixon had been charged with a crime.

In a move that was controversial at the time but that is now generally viewed as prudent, on Sept. 8, 1974, Ford granted Nixon “a full, free, and absolute pardon … for all offenses against the United States which he … has committed or may have committed or taken part in” while president.

Ford granted the pardon because, he said, he didn’t want to put Nixon, his family, and the nation through an ugly spectacle, and he justified his decision based in part on a 1915 U.S. Supreme Court decision suggesting that a pardon implies guilt and the acceptance of a pardon implies a confession.

That said, some people claimed that Ford and Nixon had simply made a mutually advantageous deal: You resign; I become president; I grant you a pardon.

Mr. Trump needs to make a similar deal, and soon. As he, uh, wrote, in The Art of the Deal, “sometimes making a deal comes down to timing.” As the ultimate deal maker, he knows—or at least he will soon figure out—that if he doesn’t act quickly, the possibility of a pardon will crumble like his plans for The Wall.

This is so for two reasons: First, although Mr. Pence was embarrassed in the Flynn matter, he has so far managed to stay fairly clear of the madness. The longer Trump waits to make the deal, however, the greater the likelihood that Pence will take another hit, and the more damage Pence suffers, the less cooperative he will be.

Second—and this is the more cogent reason—Trump knows that the dam that’s been holding back a multitude of legal actions against him and his associates could burst any time now. Congress has remained in check because Trump still has a strong base of support, but the closer the 2018 Congressional election gets, the more nervous our legislators will be about a White House in chaos, and Congress could pull the trigger any day of the week on the emoluments issue, the obstruction issue, or both. Meanwhile, it’s just a matter of time before the FBI brings charges against at least some of Trump’s associates—or even against his family members—or even against Trump himself. The Sword of Damocles was nothing compared with the variety of sharp objects hanging above Mr. Trump’s head.

Now I’m going to put on my psychologist hat and say something else no one is saying but lots of people are probably thinking: No matter how outrageous or reckless his behavior, Mr. Trump takes pride in what he did and then blabs about it. This is his style, his personality—it’s who the man is. Whether he has screwed the IRS, stiffed contractors out of money, fired his FBI director to take the “pressure” off, revealed classified information to the Russian foreign minister, or grabbed a few vaginas—it doesn’t matter; Trump crows about what he has done, sometimes grinning or chuckling as he does so.

On July 27, 2016, during a speech in Florida, Trump said, “I will tell you this, Russia: If you’re listening, I hope you’re able to find the 30,000 [Clinton] emails that are missing.” Given the pattern of behavior he has demonstrated repeatedly for much of his adult life, how can anyone doubt that, while on the campaign trail, Donald Trump “hoped” to his associates that they would get the Russian government to help him get a few votes, just as he “hoped” to Mr. Comey that he drop the investigation against Michael Flynn?

When you think about Trump from a behavioral perspective, it’s almost impossible to imagine that he did not encourage the Russians to help him. To Trump, this would have been yet another of his brilliant and advantageous deals. Trump had been trying and largely failing to get major real estate projects going in Russia since at least 1987. Conspiring with the Russians to take down Hillary Clinton would further his business interests in Russia no matter how the election turned out.

Trump needs to make the deal with Pence, but what Trump himself calls his “makeup” might get in the way: “I fight when I feel I’m getting screwed,” he said in Deal, “even if it’s costly and difficult and highly risky.”

Will his makeup prevent him from schmoozing the VP? Maybe, but it’s not just Trump who’s on the line; some of his family members are too. With all his faults, Trump seems to be as loving and loyal as a father can be. To protect himself, his business, and his family, Trump needs to get both himself and his loved ones off the hook—in other words, to make a better deal than Nixon did —to make a “beautiful” deal.

To Trump, that possibility might seem irresistible.

Dr. Epstein (@DrREpstein) is Senior Research Psychologist at the American Institute for Behavioral Research and Technology, the author of 15 books, and the former editor-in-chief of Psychology Today.