How can abortion rights be more effectively defended?

Although the biblical case against abortion is weak, the religious right has gained much traction against abortion rights in the last decade or two. The "personhood" movement is growing every year, and incremental restrictions on abortion have mushroomed. Even more alarming, the demographics seem to be against abortion rights: young people are increasingly opposed to abortion. What can be done to more effectively defend abortion rights? Can any lessons be drawn from the success of the campaign for gay marriage?