For months, the election’s trajectory has been clear.

It comes down to swing states. And to put it more bluntly, late-deciding, low-information voters in those states whose political convictions sway like palm fronds in a tropical breeze.

If you want to reach those voters, those pop-culture saturated ones who respond to vibes rather than what their bank balances or credit-card obligations tell them, the best place to do so is the dumbest comedy show on television.

And in that sense, form met function with Kamala Harris appearing on “Saturday Night Live” in what may be her most effective campaign ad of the cycle, one that only required her to divert a flight to New York in time for the sketch.

“SNL” has never been subtle about its political leanings. Recall in 2016, when Kate McKinnon did a torch version of Leonard Cohen’s “Hallelujah” while costumed as the most idealized version of Hillary Clinton possible.

“I hate to crap on my old show,” alum Rob Schneider said years later. “I literally prayed, ‘Please have a joke at the end. Don’t do this. Please don’t go down there.’ And there was no joke at the end, and I went, ‘It’s over. It’s over. It’s not going to come back.’”

But that’s where Schneider was wrong. The show, in fact, found its final form as a repository for hand-wringing liberals and their political preconceptions.

And Saturday night showed that with a vengeance, with Donald Trump — who was not invited on the show — parodied before Maya Rudolph’s Harris began her cringe-plus interactions with the real thing.

“Keep Kamala and Carry-on-a-La”? “Kamala, take my palmala”? “The American people want to end the drama-la”??

The groan-inducing gags about the imitator and the real thing and their “belief in the promise of America” didn’t stand up as actual comedy. But that wasn’t the point.

Another salutary effect of the intro skit for the veep: It allowed her to erase skipping the Al Smith Dinner, where she could have roasted Trump in person had she not had one of her famous schedule conflicts. And it allowed her to do so with a much bigger audience than tuning into cable-news streams of that Catholic showcase event.

What’s the value of the in-kind contribution, one that clearly didn’t permit Trump equal time — sidestepping a concern “SNL” creator Lorne Michaels voiced weeks ago, pointing out how problematic it would be to “bring the actual people who are running on because of election laws and the equal time provisions”?

Federal Communications Commissioner Brendan Carr is on point when he spotlights the Harris showcase as a “clear and blatant effort to evade the FCC’s Equal Time rule.”

“The purpose of the rule is to avoid exactly this type of biased and partisan conduct — a licensed broadcaster using the public airwaves to exert its influence for one candidate on the eve of an election,” Carr asserts.

Not much to be done about it now. Sure, early voting is over in much of the country.

But Tuesday’s Election Day vote? That’s the Big Enchilada, and Democrats got all the “SNL” sauce.

And there will be SNL voters — the question is how many.

In poll after poll of swing states, we see margins thinner than deli meat. Fractions of a percentage point, representing a few dozen voters in the blue wall, as well as Arizona, Nevada, Georgia and North Carolina.

A candidate doesn’t need a 5-point boost in most scenarios. Much less will do.

NBC, “SNL” and all the actors involved in that sketch provided that, tantamount to election interference and willfully flouting conventions and rules that were respected in a bygone era.

The show itself long since lost its fastball in terms of humor or the zeitgeist.

But that’s not the point. It still has political capital.

And this weekend, it pushed all its chips toward the Democratic ticket.

If Trump loses Tuesday, will sketch comedy not staying in its lane be to blame?