Why the National Rifle Association broke so prominently with its practice of not meddling in Republican primaries is the $1,112,316 (give or take) question following Luther Strange’s thumping in the Alabama runoff on Tuesday.

By joining the GOP establishment in trying to squash the campaign of the very proudly pro-gun Roy Moore, the NRA opened itself up to accusations of betraying its dues-paying gun-rights advocates: Wouldn’t the money, asked one Alabamian in a sneering letter to a local paper, “have been better spent against an anti-gun liberal or legislation?”

But as Robert Spitzer, a gun-politics guru at the State University of New York/Cortland, told my colleague Mike Spies, the NRA has its own dues to pay in Washington. They take the form of fealty to its powerful friends — especially Mitch McConnell, who feared (accurately) that a Strange loss could embolden the Steve Bannon wing of the party and spur institutionalists to retire rather than confront primary challenges from the right flank. The Washington Post yesterday published a smart breakdown of those falling dominoes.

McConnell used the NRA to unify his caucus when Democrats held tripartite control of the capital in the first years of President Barack Obama’s tenure. In return, McConnell helped the NRA block bipartisan gun-reform legislation in the wake of the Sandy Hook and Orlando mass shootings.

Said Spitzer: “It’s about fortifying those connections. They could have spent less, but they wanted to put down a significant money marker that suggested they weren’t making merely a token contribution.”

To get its legislative agenda through the Senate, the NRA will need the full commitment of McConnell, who is juggling a distinctly full plate. Simple as that.

But this is the same NRA that continues to stoke populist rage through its apocalyptic messaging. While it works to foment anti-establishment ire, it finds itself unable to stop the insurgent candidates who feed on that anger.

It’s a safe bet that any Republican who eventually succeeds McConnell as head of the GOP caucus will be equally, if not more, gung-ho about gun rights.

He or she will also preside over an increasingly dysfunctional institution, mired in grandstanding and gridlock by the same “no compromise” mentality that the NRA has had a hand in fomenting.

And that threatens to leave the NRA making a lot of noise, with few or no new pro-gun laws to show for it.

In the meantime, it failed to keep Roy Moore out of the national spotlight, where he may repeat his ultra-fringe views on guns, which include the belief that mass shootings are God’s punishment for our sins.

For all its scorched-earth rhetoric, one of the NRA’s big projects is to try to normalize guns in mainstream life. Having a radical like Moore gain a Senate platform may not help with that, either.