Why Voucher Advocates Don't Use The Word "Voucher"

I was struck yesterday that Ryan Boots at edspresso didn't want to use the word "vouchers" and instead used the word "choice," but now I understand a little better: "About a dozen Republican candidates are being propped up with money from Parents for Choice and its network of supporters, " according to this story in the Salt Lake City Tribune. "Some candidates openly endorse vouchers. But several of them avoid talking about school choice. Vouchers are unpopular with voters, polls show. "

UPDATE: In response, Boots first explains that vouchers are only one kind of choice (the best kind, I'm sure) , and then admits that the word has become "pretty much toxic" due to media compliance and opponents' efforts (Reluctant to use the "v" word?).