Mariner, you are mistaken. Over the years, the Catholic vote has gone from about 95% Democrat to 50-50, and that is due almost entirely to the abortion scandal and other moral questions.
Evangelicals, too, who are mostly in the south but can be found all over the country, mostly used to vote Democrat but now vote majority Republican. Moreover, a lot of Evangelicals formerly didn’t bother to vote, because they thought their true home was in heaven and the government was a lost cause. Now, tens of millions of those people are also voting—mainly because of abortion, family, and marriage issues.
The Republican coalition depends on social conservatives, fiscal conservatives, and those libertarian who don’t actually vote Democrat because they want free sex without consequences. Unless these factions can work together, they don’t have a prayer of winning a national election.
Republican victory also depends on the big money operators and country clubbers. If those guys try to stuff a liberal pro-abort like Rudy down the throats of the voters, they will LOSE. If they want lower taxes and other good things for themselves, they are going to have do cooperate with the base on the issues of life and family, or they will lose. You can’t win an election without money and influence, and you can’t win an election without voters. So they MUST work together or hang separately.
40% of the American public would ban abortion except to save the mother's life. I think that's a good, though not perfect, litmus test for "social conservative". The GOP is composed of 56% of those who think that way...and the Dims are 34% (wow).
Still, there could be some who would ban abortion but don't care about gay marriage, or are on the other side of the gay marriage issue.
http://www.ibis-birthdefects.org/start/news_2006_abortion.htm