The argument made by the pro-life camp is that it isn't a right. In the pro-life worldview murder is not a right, therefore abortion is not a right. In the pro-choice worldview, abortion is not murder and therefore it is the reproductive right of women to exercise that option at their discretion.
If you do not understand your opponent, there can be no meeting of the minds and thus no meaningful discussion. The true debate to be had about abortion, and the only meaningful discussion possible, is the debate over when does life and its associated rights begin. If you believe that it begins at conception then the answer is self evident in any reasonable moral system - you must not take a life without just cause. If you believe that it begins at birth then the answer is self evident again - the rights of a woman over her own body are paramount. If you take a middle stance (say, capable of living outside of the womb or similar) then you necessarily oppose abortions after that specified cutoff point.