The White House briefing that unfolded Thursday afternoon was newsworthy on more than one level. Raj Shah, a spokesman for the White House, told reporters that a background check for Rob Porter, the outgoing staff secretary, was never completed. Following allegations that Porter had abused two ex-wives, he announced his resignation on Wednesday.

“His background investigation was ongoing,” Shah said. “His (security) clearance was never denied, and he resigned.” As The Post’s Aaron Blake points out, Shah told the assembled media that White House Chief of Staff John Kelly changed his view of Porter once photos of the alleged abuse surfaced. Kelly had initially called Porter a “man of true integrity and honor, and I can’t say enough good things about him.”

Bungling from the White House led to a volley of questions about Porter and his employment. What, precisely, happened in the security clearance? Who knew about these allegations? When did they know? Jim Acosta, CNN’s chief White House correspondent, pressed Shah on just how the White House could have stood behind Porter.

A stunning response came forth: “I think it’s fair to say that we all could have done better over the last few hours, or last few days, in dealing with the situation, but this was a Rob Porter that I and many others have dealt with … and the emerging reports were not reflective of the individual who we had come to know.”

Later in the briefing, Shah was asked to specify the errors. He declined to do so.

Still — this is progress. For fear of getting busted by the Twitter gotcha gang, the Erik Wemple Blog will not say that official representatives in White House briefings have never admitted fault, never admitted weakness, never admitted an errant tweet. After all, former press secretary Sean Spicer did apologize for his Hitler-Syria debacle. We will say that such an admission is so rare as to qualify as an immediate news story on its own, regardless of the surrounding circumstances.

That’s because White House officialdom, if it has been consistent on any one thing over a year in office, has never wavered in finding new and straight-faced ways of denying prima facie blunder after prima facie blunder. This is the double-down White House, as per the following action reports:

That last one should be in every White House reporter’s toolkit.

The unrepentant culture comes from somewhere very definitive: the boss. For how many outrages and slanders and stupid frivolities has Trump failed to apologize? The count would take days. “I think apologizing’s a great thing, but you have to be wrong. I will absolutely apologize, sometime in the hopefully distant future, if I’m ever wrong.” Such an outcome materialized after the “Access Hollywood” tape (“grab ’em by the you-know-what”) in October 2016, not to mention a recent quasi-mea culpa over retweeting a far-right group.

But: Shah admitted to a sort of generalized dysfunction in the White House as it dealt with a sensitive issue. That couldn’t please the 45th president, could it? We’ve asked Shah to specify whether he’d cleared his inculpatory line with his bosses, and we haven’t heard back. If he did, good for him. If he didn’t, better for him.