not gonna lie, this improves my opinion of both blacks and democrats

There are echoes of Britain's Red Wall — the English communities identified by @JamesKanag which had conservative demographics and attitudes but had stopped short of voting Tory due to a long-held sense that the party was not for them.

@SnappyIsMyWaifu believe the saying is:

"You could put a red rosette on a pig and they'd vote for it"

Trump for prison (to secure the black vote)