A video still from a commercial for Ed Gillespie’s 2017 campaign for Virginia governor. (Courtesy Ed Gillespie for Governor)

What happens when Mr. Nice Guy meets the Blair Witch Project?

No, it’s not a pitch for a send-up of the horror movie franchise. Rather, it’s a question about what happens when Republican Ed Gillespie — a nice, diligent, wonkish guy who really wants to be Virginia’s next governor — decides it’s time to slap a big dollop of horror into the political ad wars.

According to an article by The Post’s Fenit Nirappil and Laura Vozzella, the Gillespie campaign now has four ads running in various media markets linking Democratic gubernatorial nominee Ralph Northam to violent MS-13 gangs.

Because Northam voted against a bill that would have banned sanctuary cities in Virginia (more on that later), the Gillespie campaign wants voters to believe that Northam would throw open the commonwealth’s doors to illegal immigrant baddies who would visit unspeakable horrors upon the populace.

Just in case no one gets the message behind the ad, it begins with an image right out of the “Blair Witch” basement: a sepia-tinted, hooded figure, his back to the camera, with a baseball bat resting menacingly over one shoulder as the words “kill, rape, control” flash over the screen.

Putting aside the triple-bank-shot logic it uses to link Northam to MS-13, it’s also misleading (never mind that Virginia has no sanctuary cities).

That’s the conclusion FactCheck.Org came to when it reviewed the legislative shenanigans at the heart of the ad’s claim about Northam.

According to FactCheck:

As lieutenant governor, Northam only votes in the case of a tie in the state Senate. That happened when Thomas Norment, the Republican majority leader, voted with Democrats against the bill, causing a 20-20 split. (Republicans have a 21-19 majority.)

After Northam’s subsequent “nay” vote momentarily killed the bill, Norment moved to hold another vote. The bill proceeded to pass when Norment switched sides and voted with his fellow Republicans. The bill, which also passed in the House of Delegates, was later vetoed by McAuliffe, the Democratic governor.

Northam’s team accused Norment of plotting to force the lieutenant governor to make a vote that would later become irrelevant.

“Norment declined to comment, and later grinned as a reporter tried to coax out information on whether the Senate majority leader was colluding with the Gillespie campaign to set up the lieutenant governor,” according to the Richmond Times-Dispatch.

Of course it was a set-up. And the Gillespie campaign is running with that vote, it hopes, right into the Executive Mansion.

The conventional wisdom says such ads motivate the base and move undecided voters to your candidate’s column. That’s why Democrats immediately decried the ad as Gillespie’s Willie Horton moment. They feared the possible consequences.

But the history of that infamous though little-seen ad from the 1988 presidential election, offers a cautionary tale.

Writing in  The Post back in 2016, George Washington University political scientist John Sides said the “legend” surrounding the Horton ad and how it sank Democrat Michael Dukakis’s presidential campaign “is largely wrong.”

The “attacks on Dukakis disappeared after the use of Horton as a campaign message was framed as a racially coded appeal,” Sides wrote.

A crucial difference between George H.W. Bush’s presidential campaign then and Gillespie’s gubernatorial bid now is that Bush was trending ahead of Dukakis in the polls beginning in August 1988. So far, Gillespie has consistently trailed Northam in polls of the Virginia contest, though the race is undeniably close.

But what about the other homage in Gillespie’s ad?

In case you couldn’t hear it, it’s a dog whistle that echoes Donald Trump’s presidential campaign kick-off statement regarding illegal immigrants from Mexico and the troubles they bring to America:

They’re sending people that have lots of problems, and they’re bringing those problems with us. They’re bringing drugs. They’re bringing crime. They’re rapists. And some, I assume, are good people.

Trump toppled the conventional wisdom pillar and post as he marched into the Oval Office. Maybe Gillespie thinks a slightly more subtle approach can work again, one not using Trump’s words (and never his name) but a dog whistle wrapped around a legislative sleight of hand shrouded in a horror movie cloak.

That’a a triple bank shot that requires a lot of skill — and even more cynicism — to work.