She is a center-left Democrat. I don't know if a socialist can win in today's America, unless if Trump or Cruz is the nominee. Her toughest GOP opponent is Rubio, Kasich, but they are not leading with the base of the G.O.P. right now. She could do well against Marco Rubio especially if his scandals from Florida arise.
I think the country is in an anti-establishment mood though and that an outsider like Sanders who actually strikes people as genuine and talks about issues like income inequality would be more exciting then Hillary in spite of how he labels himself.