It's possible to be against abortion and be willing to compromise on it because there are much more important issues for you to consider.

Political parties like to pretend they have monopolies on certain positions, but that's just wrong. You'll find lots of gay rights-supporting Republicans and a whole mess of pro-gun Democrats. Some voters are rational enough to realize that they should put more weight on the issues that directly effect them than the nice-to-have emotional stuff that doesn't.