I have voted for Ted Cruz twice – once as Senator and again this spring in the Texas presidential primary. One of the reasons for the latter decision was Donald Trump’s penchant for making stupid, inflammatory comments — including insulting heroes like Senator John McCain and (even worse) demeaning members of the Cruz family.

That said: Senator Cruz’s failure to endorse Donald Trump during his speech last night at the Republican Convention helped make the election of Hillary Clinton more likely. Whatever else the senator was trying to accomplish, that jaw-dropping failure was unforgivable – and quite possibly unforgettable.

The crowning irony was that the earlier portions of his speech presented an eloquent restatement of why conservative principles are as important for the 21st century as they were in 1776. And why the American Constitution and even our rule of law are threatened by executive fiat and a refusal to place justice above political considerations.

But then, as if he meant to repeat the recent mistakes of FBI Director James Comey, Senator Cruz leaped to a conclusion utterly at odds with his earlier recitation of those stubborn facts. Americans, the senator argued, should “vote their conscience” in November. Really? Wasn’t it the task of Senator Cruz to point out to a Republican Convention precisely what a well-instructed “conscience” might be suggesting, both to the assembled delegates and to the now badly mystified TV audience? Just as I had done two weeks before while watching the aberrant conclusion of FBI Director Comey, I listened in shocked disbelief as Senator Cruz wound up his remarks, shouting a single word back at the TV: “Dammit!” (repeated twice in utter disgust).

As a military officer, I grew up in a culture where the fortunes of peace and war occasionally required Army leaders to issue a traditional Navy command: “All hands on deck.” Whatever the crisis, there was a common understanding that the survival of the unit outweighed any lesser consideration – personal or preferential, philosophical or partisan. Whether that duty meant picking up a rifle, manning a fire-hose or joining in an impromptu “GI-party” before a surprise inspection, a common bond of obligation united leaders and followers alike. From top to bottom, every member of the unit assumed that survival outweighed every lesser consideration.

So it was last evening with Senator Cruz, who knows as well as anyone the political and security disasters that would inevitably attend President Hillary Clinton. Yet he left his own party naked and confused before what will certainly be an impassioned Democratic response. Senator Cruz was followed by the redoubtable former House Speaker Newt Gingrich, who underlined how a future under President Hillary would be a clear and present danger. Fox News anchor Brit Hume brilliantly described the former speaker’s task as “A clean-up on Aisle 9” — but it still left the GOP convention in utter disarray.

So what happens now?

1. Much depends on Donald Trump’s acceptance speech. He must persuade uncommitted voters that he has put his history of obnoxious mistakes well behind him. Equally important, he must unify his own party if the badly fractured GOP is to have any chance of preserving its current congressional majority, much less winning the White House.

2. Assuming they can get their national-security act together, Republicans are likely to be helped by future disasters at home or abroad. As I pointed out in this space last week, the short-changing of American defenses under Barack Obama will define his legacy – or possibly re-define it as a prelude to tragedy.

3. Winston Churchill famously said that in war you can only be killed once but in politics many times. While Senator Cruz has cornered the market on ill will for the time being, it is premature to dismiss him entirely. But make no mistake: Future opponents like HUD Secretary Julian Castro will relentlessly pursue this mistake in hopes that a suddenly vulnerable Ted Cruz will make others.