Romney is completely unreliable on abortion and just about everything else as well. But he is not a radical abortionist like Obama is. Check out Obama’s record on the infant born alive legislation. Before this legislation was passed, aborted babies could be born alive and then just left to die on their own. Obama actively supported continuing this practice, even after the U.S. Senate voted 98-0 to ban it. Then Obama brazenly lied about his position on national TV, displaying indignation when called on it. Not even people who support Roe V. Wade support this abhorrent practice, but Obama did.
The video Jim posted is incredibly damning, but in my view Obama is beyond radical and poses and existential threat.
Romney = philosophical threat
Obama = existential threat