Why do you attribute it to welfare instead of the habitual villainization of single mothers by Republicans? I wouldn't vote for someone who disparages my life situation, particularly if it were a difficult one.
This is the first I'm hearing of this. I know the right is against "leeches," but I've yet to see them single out single mothers.
Unless you're referring to undertones in their (Republicans') way of conduct. If so, then I wouldn't expect single mothers to be able to recognize the subtlety.
That kind of language, in various forms, has been a dogwhistle of the right since Reagan started saying it at campaign rallies.
Though, I am surprised that the term is hovering around 25%.