1. His position on abortion. (I’m a conservative, not a libertarian)
2. His defense of RomneyCare.
He is pro-life on all the abortion indicators: funding, judges, parental notification, gov't out of it. The statement that a woman should consult with her doctor is both a false premise & ambiguous, and is no indication that it represents a pro-abortion viewpoint. Doctors are not theologists.
Reality: You have two choices. You have Coakley who'll continue the pro-abortion status-quo, and you have Brown who's libertarian on the issue but could become conservative like Fred Thompson did during his term. You have the faux "Tea Party" candidate who's also pro-abortion and pro-homo marriage. Who are you going to support?
2. His defense of RomneyCare
If he voted for Romneycare but is now coming out against Obamacare, then I can forgive him. Like I said, he probably seen the destruction of RomneyCare to his state and changed his mind. I don't think he actually defended Romneycare considering his opposition against Obamacare.