And who will they vote for? A guy from a polygamous background, or another guy from a polygamous background?
Heck, remember, the Jews have a polygamous background, and the Christians too, inasmuch as the Old Testament is a part of our Holy Writ. Though we (Jews and Christians) haven't practiced that for millennia.
If you're alluding to Mormon vs Muslim, the Mormons have officially discountenanced polygamy for several generations.
As far as I know, only the Muslims have formal, approved polygamy these days. Them and some of the animists, I reckon.