The reason it is wrong for the government to compel or prohibit abortions has nothing to do with whether or not abortion is murder. The inside of your body is outside the jurisdiction of the government just as if it were in a sovereign foreign nation.
2. From a historical standpoint it is a very new perspective that life begins at conception. Traditionally life begins and ends with the beginning and ending of breath. The ideas of breath and spirit are closely related as seen in the word for breath, respiration.
From a scientific standpoint it is also difficult to sustain. Identical twins do not separate at conception but several weeks later. Does the second twin obtain a soul when it divides? If the soul doesn't come into being until weeks after conception perhaps it doesn't come into being until birth.
3. I am impressed by the depth of emotional commitment seen in the pro life activists and wonder about its source. They seem to have much greater rapport with the unborn than most people. Why? Since pro life positions are commonly associated with strong religious beliefs this may be the key.
A strong belief in the afterlife changes one's perspective on life on this earth. If a future life as an angel is more real and present than this life on earth then life here is experienced as an unborn angel. Experiencing daily life as an unborn higher being would certainly give one great rapport with the unborn humans and threats to their lives would be deeply felt.
4. There is a solution to this problem after all but it comes from science and may therefore not be acceptable to either side. The technology to freeze embryos in liquid nitrogen was developed for the livestock market and the basic procedures are now well understood. Frozen embryos are not dead and therefore their souls are not lost. They are transported into the future which will hopefully value them more than we do now. They may repopulate the world after a plague or populate another world far away. Thousands can be stored in a small space and the cost of liquid nitrogen is falling all the time.
The pro life movement now has a positive solution it can offer. They can open their own abortion clinics where the embryos will be frozen thus saving the souls of the unborn for a future life in a better world. Most mothers to be would want their unborn children to have a chance at life in the future and this is exactly what the pro life activists also want.