As I write this, the government shutdown is in its 19th day, with Donald Trump using the threat of a presidential veto for appropriations bills that might reopen the government unless he gets $5.7 billion for a border wall.

Why is Trump being so stubborn about this one issue? There are political answers to this question. He’s determined to keep a campaign promise. The border wall has become his signature issue. But the truth of the matter has nothing to do with any of that. It’s far more basic, and he’s told us what it is himself:

“I would look foolish if I did that.”

With Trump, this obviously isn’t about government workers going without their paychecks. But it’s not about political calculus, either. It’s not even about the wall. It’s about his visceral obsession with always “winning” — or at least looking like a winner. Trump lies a lot, and it’s this obsession is what leads him to tell most of his lies.

Trump has built up a formidable image over the years based on a few successes and his own continual self-promotion. Maintaining and augmenting that image is, and has always been, Job One for him. That’s why he ran for president: It was the next logical step in advancing the persona being generated by his outsized ego.

So, naturally, he is obsessed with saving face — to use his words, with not looking foolish. This is the motivation behind his bald-faced lies about everything from the size of the crowd at the inauguration to the depth of his knowledge on virtually any subject:

“I know more about renewables than any human being on Earth.”

“I think nobody knows more about taxes than I do.”

“Nobody knows more about trade than me.”

“I know more about (the militant group) ISIS than the generals do.”

Jekyll and Hyde

Trump’s constant focus on self-aggrandizement and saving face also explains what seems like an odd dichotomy. Those who meet him in person often describe him as gracious, even solicitous (witness his behavior toward Vladimir Putin and Kim Jong Un), but if you cross him, or even just contradict him, he can unleash scathing attacks that range from juvenile name-calling to full-throated character assassination. He’s a veritable Dr. Jekyll and Mr. Hyde.

Consider his love-hate relationship with the media: They’re the most reliable means available to relay his propaganda, and when they do so – as Fox News has done – he sings their praises. But when they call his bluff, as CNN and The New York Times have dared to do, he turns on them like a rabid dog because they threaten the image of himself he’s so carefully crafted.

Witness also his treatment of people like James Mattis, Michael Cohen and Jeff Sessions. There are others, but these three will suffice to make the point. All have been on the receiving end of Trump’s effusive praise and, later, his scornful derision. The men themselves didn’t change; their response to Trump did. And for one reason: At some point, Trump’s version of reality became a bridge too far for them, as it always seems to. He pushes and pushes until the pressure becomes untenable, and something has to give.

Trump forced Mattis to choose between him and what the general considered to be the nation’s best interests in Syria. He forced Cohen to choose between him and Cohen’s freedom/family. He forced Sessions to choose between him and the rule of law.

The only thing

The question is, what will happen when he forces his supporters to choose between him and something they really, really care about?

Now he’s forcing them to choose between his wall and a government shutdown that’s keeping federal workers from receiving their paychecks and could threaten the nation’s credit rating. Rest assured, this is only the beginning, because when Trump gets his way, he always pushes harder. Mattis and Cohen both reached a breaking point and said “enough.” The question is, what will cause Trump’s base to reach that breaking point. Will it be an economic meltdown? A Constitutional crisis? Something else?

Trump has been masterful so far at “holding” his base, because that base has projected its own hopes, dreams and worldview onto him. He’s made this easy for them, because he's basically a blank slate. Trump has seldom adhered to core principles on anything, apart perhaps from trade, because principles get in the way of building and maintaining an image. He’s gotten his supporters to buy into his way of thinking: Principles aren’t important; winning is. And for the sake of “winning,” they’re willing to sacrifice everything from their views on morality to free trade to the national debt.

Trump and his supporters epitomize what Green Bay Packers coach Vince Lombardi once said: “Winning isn’t everything. It’s the only thing.”

Breaking point

And therein lies, I think, the answer to my question: Trump’s base will desert him when he’s no longer winning. In other words, Trump’s goals and theirs line up perfectly, which explains why they’re so solidly behind him. It’s a symbiotic relationship. Trump has gotten his supporters to buy into the idea that his success is their success, and that his failure will be theirs. And he’s taught them how to avoid that failure: through denial, fabrication and the demonization of one’s enemies.

Trump has succeeded in making his followers see themselves as an extension of himself, which is certainly the way he sees them. When he decries journalists as “the enemy of the people,” what he’s really saying is they are the enemy of Donald Trump. “The people” are merely Donald Trump writ large. This is why it wasn’t enough for him to win the presidency thanks to the Electoral College; he had to complain that he really won the popular vote, too, and only election fraud had prevented that from happening.

Shifting blame. It’s one of Trump’s core strategies in dealing with failure: He hasn’t really failed; it just looks like he has because his nemesis — whether it be “the Democrats” or Mueller or Obama or “Crooked Hillary” — have pulled a fast one.

Which brings us back to the shutdown. Trump doesn’t think his usual tactics will work this time. When Limbaugh and Coulter warned him about what would happen if he didn’t stick to his guns on the wall, he got scared. And South Carolina Sen. Lindsay Graham was even more direct: “If he gives in now, that's the end of 2019, in terms of him being an effective president.” Trump clearly believes that failure to secure funding for the border wall would be one defeat he won’t be able to gloss over by spinning or blaming on his opponents.

This sort of maneuver could still be an option: If he declares a state of emergency that leads to litigation, he could, conceivably, shift blame to the courts. Even so, when conservative pundits Rush Limbaugh and Ann Coulter stood up to him, Trump blinked, and now he’s trying desperately to salvage his image by refusing to blink in a staredown with Democrats over the shutdown.

But “Chuck and Nancy” may have learned something from Rush and Ann: It’s possible to stand up to Trump. Now he’s backed himself into a corner with very few options for saving face, and they have the advantage.

Keep in mind, however, that a cornered animal becomes desperate — and dangerous — especially when the thing it values most is at stake. And the thing Trump values most, his image, is at on the line here, which means the year ahead could be very ... interesting.