Donald J. Trump more or less vowed to be an unconventional president while he campaigned for the office. Man, he’s made good on that one, eh?

Consider what he said after the failure of the Republican caucus in the Senate to repeal and replace the Affordable Care Act.

“I won’t own” the failure, he said. He wants to let the ACA fail and then he’ll swoop in to clean up the mess — assuming, of course, that it even happens.

How disgraceful.

President Truman famously had that sign on his Oval Office desk: “The Buck Stops Here.” President Kennedy told us after the Bay of Pigs disaster in 1961 that “victory has a thousand fathers, but defeat is an orphan”; he took the hickey for the invasion’s failure. President Reagan admitted to making a mistake during the Iran-Contra controversy, that he didn’t believe “in my heart” that he was trading arms to a hostile nation; he “owned” it eventually.

The current president? He’s not standing by the stumble-bum effort in Congress to enact this legislation. Republicans had seven years to come up with an alternative to the ACA, which they despise largely — or so it seems — because it has Barack H. Obama’s name on it. They call it “Obamacare” as a term of derision.

They blew it. As head of the Republican Party, so did the president. He owns this mistake, whether he cares to admit it or not.

Presidents Truman, Kennedy and Reagan all knew how to stand behind their failures. They all understood that the terms of the office they required them to do so.

Aw, but what the hell. They were just your normal run-of-the-mill politicians who played by the rules. The current president doesn’t operate under the same precept of full accountability.