The Republican base hates the healthcare bill that was passed in '09, or what they like to call it: "Obamacare". That was based on his healthcare plan in MA. Due to that I highly doubt he'll even be a front runner in the GOP primary. His adversaries would definately use that bit against him, and probably successfully succeed in doing so.
I don't know if I'd support him though. If he's like any of the other typical GOP members in Congress who want tax cuts for the rich, cut unemployment, abolish Roe V Wade, etc. then no.