What would be worse in the White House, a crazy man or a coward?

The question came to mind last week after U.S. Sen. Angus King announced he’ll vote for Hillary Clinton come November.

King’s primary reason, as he told CNN’s Chris Cuomo: Unlike Clinton, Republican Donald Trump lacks the “judgment and temperament” needed to be president, as well as the “kind of coolness” required when time is of the essence and there’s no substitute for thoughtful, courageous leadership.

King cited, as an example, a ride he took recently on the National Airborne Operations Center, also known as the “Doomsday Plane,” designed to provide mobile command and control in the event of a nuclear attack on the United States.

On the drill, which included an Air Force officer playing the role of the president, a tracking device depicted the launch of enemy missiles while a clock showed 28 minutes and counting.

“That was the time the president had to make a decision,” King recalled. “What got me – it was almost physical – was that in that situation, there’s only one person. There’s no checks and balances, there’s no Congress, there’s no Supreme Court, there’s no consultation. There’s one person making a decision about the future of civilization.”

King’s conclusion: With information pouring in from all over creation (Are they really missiles? Could they be something else?) and precious little time to digest it, Trump is not “somebody I would be comfortable with.”

In other words, Trump very well might make a rash decision we might all later regret – assuming we were all still around to regret it.

But here’s another scenario: Faced with a hugely dangerous situation, the kind that demands equal applications of calm and courage, Trump panics. He freezes. He shuts down.

Impossible?

Once, and only once, during his 13-month campaign have we seen Donald Trump in a truly unguarded moment. A moment when something not only unexpected happened, but something downright scary.

It happened on March 12 at a rally in Dayton, Ohio. As Trump spoke to a cheering crowd inside an airport hangar, a lone man leaped over a barricade and rushed toward the stage before being tackled and carted off by alert Secret Service agents.

Trump, who never saw the guy coming, was alerted by crowd members immediately in front of him.

Panic in his eyes, he lurched to his right, saw the scrum already underway, grabbed hold of one of the four agents who quickly surrounded him and, upon receiving the all clear, shakily turned back toward the microphone.

His face glimmered with sweat. He grabbed the lectern with both hands as if to steady himself, then turned and walked away to watch as the Secret Service dragged the miscreant across the tarmac.

Returning to the lectern, arms extended with both thumbs up, still perspiring, Trump told the front row: “Thank you for the warning. I was ready for him, but it’s much easier if the cops do it, don’t we agree?”

To be clear, this was not just a routine hiccup on the campaign trail. Trump had good reason to be startled the second those people in front of him began screaming and pointing at something not good unfolding behind him.

What made it such a defining moment, though, was Trump’s painfully futile attempt to keep playing the tough guy, to keep up that pugilistic façade, even after he’d clearly just had the daylights scared out of him for all the world to see.

Was he really “ready” for that fence jumper? Not a chance.

In that split-second, fight-or-flight moment, Trump chose flight.

And then, only after the stage was secure and his assailant was safely in handcuffs, did he oh-so-bravely insist he’d been prepared all along to fight.

Talk of fighting – against ISIS, against Hillary Clinton, against immigrants, against the “establishment” – will fill the air this week as Trump descends on Cleveland to finally accept the Republican nomination for president.

But to mistake all of that for courage, when it comes to the Republican standard-bearer, is to willfully ignore the obvious.

Donald Trump is not a brave man.

He may bluster like one, shake his fists like one, call out world leaders and entire segments of the American population like one. But all of that comes from the safety of the podium, buffered by a crowd that greets any sign of adversity with the mindless chant, “Trump! Trump! Trump!”

Back Trump into a corner, put him in a situation that demands, as King put it, a certain “kind of coolness,” and the man goes to pieces.

Last week, just before King threw his hat into the ring for Hillary Clinton, a group of esteemed American historians launched a Facebook page (https://www.facebook.com/historiansondonaldtrump/) to explain why, to a man and woman, they think a President Donald Trump would be a disastrous thing.

Leading the “Historians on Donald Trump” charge was none other than David McCullough, a summer resident of Camden, who twice won the Pulitzer Prize for his biographies of John Adams and Harry Truman. He’s also a deserved recipient of the Presidential Medal of Freedom, the highest civilian award this country has to offer.

Trump, says the normally apolitical McCullough, “is unwise, he is plainly unprepared, unqualified and, it often seems, unhinged. How could we possibly put our future in the hands of such a man?”

My gut tells me we won’t.

And my guess – my fervent hope – is that as November draws near, events will conspire to unmask Trump once and for all.

It could come during a debate when there’s no cheering crowd to obscure the sight of Trump, like a deer in the headlights, paralyzed by the simplest of foreign policy questions. (“Turkey? They love me over there. They think I’m terrific!”)

It could come when his tanking poll numbers prompt him to quit rather than suffer a humiliating defeat – the one thing that seems to scare him above all else.

It could come when the avalanche of opposition TV ads, all starring The Donald, slowly drown him in his own cauldron of cowardice masquerading as courage.

Angus King is right. Donald Trump indeed lacks the judgment and temperament to hold the future of the planet in his own two hands.

He also lacks the guts.