They might get some Libertarians, but they would lose the soccer Moms in droves. Go for it.
Well, I hope you're right if it happens, but my guess is they'd have a electoral lock for a long time. They have no conscience about lying, so I would expect to see it framed emotionally as another "we'll protect you from the mean judgmental religious Republicans" or "more money for hospitals than jails" issue, and harp on the "unfairness" and "racism" of the whole prohibition scene.
The Klan party turned on a dime when it was clear they couldn't keep [minorities] in their place by traditional methods any longer; I wouldn't put ending the WOsD beyond them.