Interestingly enough, the legal case for overturning Roe v. Wade (as opposed to the moral case against abortion) doesn't turn on affirming a fetus's constitutional right to life, but instead on denying a woman's absolute right to privacy, which according to Roe's critics, is an invented right which is the product of judicial activism. Here is some information on the debate concerning the right to privacy.
It seems to me there are four possible positions here. You could accept the court's defense of the right to privacy, but still consider abortion to be murder, you could reject the court's defense of the right to privacy and consider abortion to be murder, you could accept the court's defense of the right to privacy and deny that abortion is murder, or you could reject the court's defense of the right to privacy, but deny that abortion is is murder.
The first and fourth positions seem to be, at least consistent, though they put you in a bit of spot reconciling your moral and legal philosophies. In the first place you are stuck saying that abortion is murder, but it has to be legal to protect a woman's privacy. In the second case, you think abortion isn't murder, but there is no legal basis for stopping the government from legislating against it.
Here is a discussion of the legal issue of privacy.