Former Democrat Donald Trump speaks at a rally in Exeter, N.H. (Joe Raedle/Getty Images)

Of the many people Donald Trump praises in his 1987 book “The Art of the Deal,” one of the first is Mario Cuomo, who was then governor of New York and one of the more estimable liberals in the country. Cuomo, Trump writes, was “a winner and a good guy at that.”

He wasn’t the last Democrat who got some love in “The Art of the Deal” or in the broader Trump oeuvre. The following year on “Oprah,” handicapping the 1988 presidential race, Trump said entirely nice things about Michael Dukakis and Jesse Jackson. There’s a now-rather-notorious 2005 picture of Trump and Melania Knauss at their wedding reception, palling around with Bill and Hillary Clinton. In 2009, he was optimistic about Obama and wrote that the new president had “surrounded himself with very competent people, and that’s the mark of a strong leader.”

Now that Trump is running for president as a Republican, it’s all rather discordant. Trump did not register as a Republican until 1987, at age 41. He went Republican for a dozen years, served a brief tour in Ross Perot’s Reform Party, then joined the Democratic fold for most of George W. Bush’s presidency. He was a registered Republican in 2009 and 2010, an independent in 2011, and then a Republican again in 2012. It’s entirely possible that he would have switched back to the Democrats if President Obama had shown him a bit more love when Trump offered in 2010 to help the administration plug the BP oil spill in the Gulf of Mexico and to build a new White House ballroom.

This past week, it looked like Trump’s political past could drag down his future. In the days just before its caucuses, Iowa was inundated by super-PAC-funded ads that hammered the billionaire for his past liberal views. Late deciders in Iowa voted overwhelmingly for other candidates, caucus entrance polling showed.

The ads, and Trump’s opponents, are making what seems like a common-sense argument: This guy’s not to be trusted. He’s not one of us. It’s proving somewhat effective. But it ignores the GOP’s long and productive history with political refugees from the other side. It’s also vulnerable to precisely the kinds of counterarguments that past turncoats have successfully made and that are intimately connected to Trump’s appeal.

Most people understand intuitively the fundamental discomfort of partisan identity. Very few of us fit perfectly into the political suit we’ve chosen or been given to wear. It would be strange if we did, since at any given time the suits on offer are patched together according to complex social, political and historical patterns that are unlikely to overlay perfectly the equally complex ecosystems we inhabit as individuals. We pick the suit that fits us best and deny, ignore or just muddle along with the ways it doesn’t feel quite right. A political identity is always a negotiation between what it demands and who we are. The suit can fit for a while, for meaningful reasons, and then grow too tight or too loose, also for meaningful reasons.

Trump has changed parties. Yet it’s clear to everyone, even those who detest his politics, that whatever his partisan affiliation has happened to be at a given moment, he’s never wavered in his nativism, his obsession with “winning” or his celebration of business acumen and common sense as the highest political virtues.

From one angle, Trump’s frequent party-switching looks like evidence of indecision or opportunism. This may have been what cost him victory in Iowa. From another perspective, which suited about a quarter of the Iowa Republican electorate, it’s proof of authenticity and decisiveness.

In “Crippled America,” his most recent book, Trump devotes a few paragraphs to the charge that Republicans shouldn’t trust him because of his fickle relationship with the party.

He says he was a Democrat because he was born in New York, and everyone there is a Democrat. He’s always been a Republican at heart. He likes the Constitution. He’s conservative now on the big issues. And then the trump card:

“You know who else was a Democrat? Ronald Reagan. He switched, and I switched years ago, when I began to see what liberal Democrats were doing to our country. Now I’m a conservative Republican with a big heart. I didn’t decide to become a Republican. That’s who I have always been.”

The passage doesn’t exactly hold together as logic or history. It has some emotive power, though, and it does something important, suggesting that Trump’s past isn’t just a mistake that needs to be explained: It’s a potential source of strength and insight as well. He has a unique understanding of what kind of conservatism America needs precisely because he was once on the other side. He may even be better positioned to fight the liberals than anyone else in the Republican race because he knows them so intimately.

It’s a very Trump-esque maneuver, turning an apparent weakness into a strength. It’s also an old argument and one that’s been made successfully by many of his predecessors in the ranks of prominent Americans who’ve traveled from the left to the right.

Consider, as Trump did, our 40th president. Reagan’s father, Jack, was a die-hard partisan who idolized Franklin Roosevelt and even worked for a time for a New Deal offshoot during the 1930s. Ronald Reagan was a liberal Democrat for half his life, and his attachment to his Democratic identity, because of his father and because of his own admiration for FDR, was so deep and abiding that it would take him more than a decade to fully detach.

Even as his beliefs diverged more and more from the party line in the 1950s, he couldn’t bear to abruptly turn away from his past self. Reagan changed incrementally, along the way evolving an arsenal of stories, lessons, evasions and stratagems that enabled him to break from his loyalties without taking an axe to the emotional ties — of family, workplace, ethnicity, religion, history and geography — with which those loyalties had been bound up.

One result of this long, slow evolution was that by the end of it, Reagan was able to take his struggle out of liberalism and offer it to back to susceptible Democratic voters in the form of a deeply reassuring narrative. It’s not you who have changed. You’re great as you are. It’s the world around you. It’s the Democratic Party, once your home, that’s shifted.

Without this process and the resultant narrative, he would have been a far less transformative president, far less capable of selling political changes that were, in fact, quite dramatic.

By the time he arrived as his fully formed conservative self in the early 1960s, Reagan was almost entirely immune to attacks from the right over his old beliefs and affiliations. The story he told was too well developed, reassuring and integrated for anyone to see him as anything other than conservative.

Trump is more susceptible to such attacks, for a few reasons. He doesn’t have Reagan’s political skills. His conversion story is less developed and persuasive. He hasn’t cultivated deep ties to the right. And his story isn’t one of reassurance and integration, but something like the opposite: It promises rupture and discontinuity, the destruction of inhibitions and niceties.

It wants to build a big wall along the border and make Mexico pay for it. It wants to say “You’re fired!” to every bureaucrat who gets in Trump’s way. To deport 11 million people. To cut loose, or bulldoze through, binding international treaties, geopolitical balances of power and complex tax codes. It wants a world where one very big winner, and through him the rest of us, can do and be whatever we want by virtue of hard work, good values, tough dealmaking and a killer instinct.

It’s a fantasy, of course. And one that’s vulnerable to criticism. But it’s also deeply compelling to millions of people, suited not just to the political climate of our time — the gridlock, the polarization, the pessimism, the seeming incapacity to come together on great projects for the future — but to certain quandaries of being human. Who among us doesn’t dream, sometimes, of not being tied down by all the overlapping strands of obligation, expectation, hierarchy, bureaucracy, courtesy and reciprocity that constrain and condition us as we move through our lives? Who doesn’t dream that if we could just bring ourselves to break out of that cage, we might live more amazing, terrific, frictionless lives?

Trump, like many political converts before him, tells us a deep truth about who we are as a culture and where we might be going. He also poses a challenge to us, to look directly at the fears and fantasies we harbor that are going to find political form, one way or another, and to make choices about what form they will take.

Twitter: @djopps

Read more from Outlook and follow our updates on Facebook and Twitter.