When the news hit on Tuesday that the Trump campaign has washed its hands of fund-raising efforts two weeks before the election, the humiliation of the traditional Republican Party at the hands of Donald Trump was all but complete.

His refusal to help fill party coffers just as the last push for voters commences — which is an expensive process and requires cash on hand — is the perfect capper to 16 months in which Trump has gleefully terrorized weak-kneed Republican officials, forced them to comply with his wishes and then screwed them.

And it’s probably not the capper, not really; with 12 days to go until the election, who knows what final blows Trump will deliver to the kneecaps of Republican National Chairman Reince Priebus and all the elected Republican officials who have been doing the “yes, I endorsed you but I don’t really like you” two-step?

Loyalty is a one-way street in Trump World. Priebus has likely sacrificed his future being loyal to Trump in the present, since the candidate to whom he has sworn his allegiance is now effectively turning on the Republican Party’s efforts to elect candidates down-ticket — which is Priebus’ primary responsibility as RNC chair.

Priebus has no right to be surprised. From the moment the mogul came down the escalator, Trump has played him like a piano.

At first, Priebus made nice in order to secure Trump’s guarantee that he wouldn’t bolt the party after a primary-season defeat and run as an independent candidate who would split the vote on the right and thereby elect Hillary Clinton.

Trump did so in September 2015, but when it looked like he was on his way to defeat in the Wisconsin primary five months later, he explicitly reneged on it because, he said, “I have been treated very unfairly . . . by basically the RNC, the Republican Party, the establishment.”

He hadn’t been; he was sore that his faulty organization had not read the rules governing the primary processes in certain states and that Ted Cruz had gotten more delegates out of them than Trump thought he should have.

But right there, in reneging on the pledge, Priebus had a chance to save his dignity and his honor by confronting Trump with his bad faith. He didn’t, and from that moment on, Trump owned him.

Trump owned Priebus so badly that his consistent aggression against Priebus’ close friend Paul Ryan earned not so much as a syllable of public complaint or distancing. He owned Priebus so lock, stock and barrel that the suggestion of any effort to use existing Republican Party rules to challenge Trump’s domination of the Republican National Convention led to the mouse-like Priebus suddenly roaring lion-like about financial punishments and excommunications for anyone who dared cross the nominee.

Priebus was, of course, not alone in responding to Trump’s hyper-aggressiveness by cowering in fear. Most of the Republican field did so as well. Jeb Bush was so startled by Trump’s personal insults during the debates that he could do little but sputter. Ted Cruz tweeted that he would not get into it with Trump just because the media wanted him to and that Trump was “terrific,” which did not spare him from Trump calling his wife ugly and saying his father was involved in JFK’s assassination.

And, of course, after making a scene at the convention by failing to endorse Trump, Cruz later did so in a fashion that was at best distastefully conniving and at worst an act of sniveling cowardice.

As the last days approach, Priebus and others are left to wonder whether Trump is going to follow the ideological wishes of his campaign chairman Steve Bannon and try to burn the Republican Party down so that Bannon and others like him can more easily occupy the ruins. Now there’s nothing they can do to prevent the arson, and there’s nowhere for them to go to avoid being singed themselves.

All this was possible from the minute Trump became a candidate. Priebus knew it, because otherwise he wouldn’t have thought it necessary to court Trump so assiduously in the summer of 2015. That was his first mistake, and, in politics, very likely his last.

Trump could cause more problems by refusing to concede the election if he loses: