Guest-posting at Nate Silver's 538, Mark Smith makes a point that is not made nearly often enough. Pundits talk about the potential costs of Roe v. Wade and the Democratic Party's embrace of womens' reproductive freedom—lost votes among social conservatives who might otherwise be more sympathetic to Democratic economic policies. But as Smith points out, there's another side to it: relatively affluent states such as Washington that have gone from swing states to solid blue states in large measure because of Republican positions on cultural issues. In 1980, as Smith notes, "Ronald Reagan over-performed in Washington relative to his margin of victory in the nation as a whole." But a Republican Party committed to overruling Roe v. Wade is simply not going to be competitive in Washington.
It's not just Washington. Democratic liberalism on social issues is a crucial reason why states like California and New York—both of which Reagan carried twice—have become electoral college locks for the Democratic Party. (In an electoral universe in which these states were even competitive, Republican advantages in resources would be immensely difficult to overcome.) These advantages are frequently ignored when pundits urge Democrats to move to the right on social issues.
The conventional wisdom would suggest that supporting reproductive rights is, on net, a national net negative for the Democrats. I see little basis for this belief. The consistent two-for-one public support for Roe v. Wade certainly puts the burden of proof on those who argue that abortion is a net loser for the Democrats in presidential politics. Moreover, contrary to the assumption of many pundits, affluent, educated voters (who are relatively more socially liberal) generally place a higher priority on social issues than working-class voters do. To give another example, claims that same-sex marriage swung the 2004 election for George W. Bush turned out to be empirically wrong. Again, too many pundits focused on the opponents of same-sex marriage that referenda might have mobilized, while ignoring the affluent suburban voters who were alienated by Republican demagoguery on the issue.
Democrats should support reproductive rights because it's the right thing to do. But in national and many state elections, doing the right thing carries substantial electoral benefits as well.