It was a moment that most of us will never forget -- waking up in the gray gloaming of an early Sunday morning and turning on a TV or a computer or looking down bleary-eyed at their phone to learn that shocking news of what had transpired in the dead of night in Orlando. You don't have to be the parent of young adults in their early 20s, as I am, to imagine the anguish of these dads or moms or friends, frantically trying to reach their loved ones who'd gone to the Pulse nightclub, and to feel a gut-wrenching blend of compassion and despair.

Who knows?...maybe Donald Trump, who's still a dad even though he wanted us to know he's not the kind who would change a diaper, felt some of those things, too. All we can say for sure is that's not the face that the presumptive GOP presidential nominee wanted to show the world on a Sunday when 49 corpses were still lying where they fell on a dance floor during the worst mass shooting in American history.

"Appreciate the congrats for being right on radical Islamic terrorism," Trump wrote on Twitter around midday, as anxious survivors continued to await word of the missing. Any sympathy for victims' family and friends would have to wait a day, when Trump stood in front of a Teleprompter in New Hampshire and struggled to stay on script. The qualities of humble human empathy and compassion that have bonded Americans and their leaders in times of mourning -- from Ronald Reagan's moving words about the Challenger explosion to Bill Clinton's healing stewardship after the Oklahoma City bombing -- were nowhere to be seen.

It would be a bad thing if The Donald's I-told-you-so, psychopathic narcissism was the lowlight of his reaction to the kind of national crisis that -- sadly but predictably -- will make or break whoever takes the oath of office on January 20, 2017. But Trump was just getting started.

In less than two days, the man who's already amassed enough pledged convention delegates to claim the Republican nomination next month in beautiful downtown Cleveland has:

-- Called for the resignation of President Obama, not over any high crime or even a misdemeanor but solely because the president, in voicing sorrow and resolve in the wake of Orlando, didn't utter the specific words "radical Islam." That odd swipe apparently didn't give Trump enough of a publicity "high," because today he came back and implied that somehow Obama -- the same president that he accused of not being a citizen in a ridiculous charade five years ago -- was complicit in the attack.

-- Not only re-proposed but expanded his plan -- branded as unconstitutional-on-arrival by anyone with more than one law-school course credit -- to ban human beings from entering America solely on the basis of what religion they believe in. This, by the way, in response to an attack committed by a 29-year-old American citizen born -- just like Donald Trump -- in Queens, N.Y.

-- Taken his own jihad -- against the concept of a free press as guaranteed by our Founding Fathers in the 1st Amendment -- to a new and alarming level by banning one of the nation's most prominent legacy news organizations, the Washington Post, from covering his campaign. For good measure, since that apparently wasn't enough flouting of the Bill of Rights for one day, the candidate also said Americans who don't report "suspicious" neighbors to the authorities would be "brought to justice" by a Trump administration.

-- Disrespected the dead by embracing his endorsement from the National Rifle Association, ignoring America's failure to ban military-style semi-automatic assault rifle like the AR-15 which has led to unthinkable body counts from Newtown to San Bernardino to Orlando, and embracing that canard that "good guys with guns" would have prevented the Florida carnage.

The broader truth is that the only good thing Trump has done in this fateful week is humiliate Chris Christie by making him pick up his McDonald's order. Balance that against news accounts that he's a deadbeat who stiffed decent small businessmen and contractors and a nightmare executive who -- contrary to his supporters' child-like belief in Trump's financial acumen -- ran his Atlantic City casinos into the ground.

Even worse, his tone earlier today in New Hampshire -- alternately bleating and bullying -- made a mockery of Trump's promise to act "presidential" now that he's clinched the nomination. The idea of this small-minded and vindictive psychopath with America's nuclear codes is 100 times more frightening than the brink-of-annihilation 1962 Cuban missile crisis. And the possibility of a President Donald Trump shredding the Bill of Rights is no longer a reality-TV-grade curiosity, but a bona fide constitutional crisis.

On Sunday, Obama told the nation that "to actively do nothing is a decision, as well." Yes, he was talking about gun violence, but the 2,472 delegates to the Republican National Convention ought to ponder the deeper significance of those words.

Yes, Trump got an overwhelming number of GOP primary votes. But, for better or worse, America's political parties aren't tried to the same rules as our fragile democratic republic. They aren't even mentioned in the Constitution. And for the first 200 years, the job of nominating their candidates fell on unbound convention delegates. If the leaders of the Republican Party mean it when they say they love America, then they must set those delegates free to vote their conscience on July 20.

I write these words as a liberal voter and as a student of political science: I fully believe that a principled conservative coming out of Cleveland would probably -- emphasis on "probably" -- have a better chance of defeating Hillary Clinton than Trump does. So, yes, I'm calling for something that would actually make the vision of a more progressive America, which I share with millions of others, a little less likely. But I've seen America borne backwards by right-wing presidents, and survive. I don't believe America, as we know it, could survive a Trump presidency.

At key moments in U.S. history, political figures have risen to the occasion and become profiles in courage. The bipartisan congressional probes of Richard Nixon is one such instance that some of us still remember. It's not too late for patriotic Republicans to again rise to the occasion. Change the party rules in Cleveland. Allow the delegates to vote their conscience on the first ballot -- and dump Donald Trump this summer. I guarantee that history would remember you as heroes.