Origin of "We're voting for the nigger"?

I’ve heard this anecdote repeated several times, both in real life and on the internet – most recently iterated by lorene in Justin_Bailey’s Fuck it, I’m counting my chickens thread.

Setting: a door-to-door canvasser knocks on a front door in [rural swing state – usually PA or WV]. A woman answers.

WOMAN: Can I help you?
CANVASSER: Hello, I’d just like to ask you who you’re voting for.
WOMAN: [calls inside house to husband] Who are we voting for?
HUSBAND: We’re voting for the nigger!
WOMAN: [to canvasser] We’re voting for the nigger.

What’s the origin of this anecdote? Why has it gained so much currency and been repeated so often?

538 was reporting about a family in PA

The original column is here. A followup comment is here:

I can’t provide a cite for this, but my brother heard this one on the radio and told me about it, some couple of weeks before I saw its appearance on 538. I don’t remember if it was specifically about the couple in Pennsylvania or if it was supposed to have happened in N.C. or some other stereotypically “racist redneck area.”

It wasnt Mel Brookes house by any chance?

I’ve seen it on fivethirtyeight.com but it’s also strongly reminiscent of the 1991 race for governor in Louisiana between convicted influence peddler Edwin Edwards and avowed racist and KKK member David Duke. Faced with a classic “lesser of two evils” choice, Louisianans sported bumper stickers reading “Vote for the Crook - It’s Important!”

A Chicago area comedian, Aaron Freeman, during the Chicago mayoral race between Harold Washington and Bernard Epton used a similar sort of phrasing in a stand up routine: “Are you voting for the nigger or the kike?” I’m wondering if the current line used in the thread title is an updated version of something that’s been around a long time and has some basis in peoples’ prejudices?

This isn’t Shakespeare. I’d say it’s just something that a basically prejudice person could come up with off the top of their head.