that this is the single most important issue for some voters.

It would seem like common sense to separate men and women's sports in such cases like this one, but who makes these decisions to let transgender women compete on cisgender women's sports teams? Is it the government, or the university? Why is it even a political issue?

I'm pretty sure that the great majority of universities do not allow this, so why do people think it is a political issue that whoever is up for election could or would get involved in?