Life opportunities: why McCain shouldn't run away from the abortion issue.(John McCain)

TALKING about social issues obviously makes John McCain uncomfortable, and he has said that he is not passionate about them. He doesn't have to become more enthusiastic. But he does need to understand that the most politically salient of the social issues, abortion, is a vulnerability of Barack Obama. To win the presidency, McCain needs to take advantage of that weakness.

McCain has consistently voted against abortion since coming to Congress. But for much of McCain's political career, the conventional wisdom was that opposition to abortion is a losing issue: Republican politicians might have to be pro-life to survive primaries, but then had to mollify the pro-choice majority in general elections. That conventional wisdom has never been true. Surveys have consistently found that pro-lifers are more likely to vote on abortion than pro-choicers, and that greater intensity has translated into a political benefit for pro-life candidates. With time, moreover, the notion that the pro-life position is a political liability has become even less tenable.

More Americans describe themselves as pro-choice than pro-life. But over the last dozen years, the margin by which they do so has shrunk to single digits. People are more willing to call themselves pro-life for several reasons, the most important being the debate over partial-birth abortion, the development of ultrasound technology, and the decline of anti-abortion violence.

The public's policy views, meanwhile, are more pro-life than their self-labeling would indicate. Gallup asks respondents whether abortion should be allowed in all, most, a few, or no circumstances. In its latest survey, from May, 57 percent chose the two restrictive options and 41 percent the two permissive ones. Independent voters (those unaffiliated with either political party) had the same basic preferences: They split 54-44 for the pro-life options.

In a June survey for the National Right to Life Committee, the Polling Company found that 38 percent of the public believed that abortion should be allowed for any reason in the first trimester (or took even more liberal views), while 54 percent believed that abortion should be allowed, at most, in cases of rape, incest, or threats to the mother's life.

The idea of a "pro-choice majority" comes from a partial and tendentious reading of public opinion. Pollsters usually find strong support for Roe v. Wade, for example, but a lot of voters seem to think, incorrectly, that to overturn Roe would prohibit abortion with no exceptions. The actual policy regime imposed by Roe (leaving abortion effectively legal at any stage of pregnancy) consistently draws support from only about 10 percent of the population.

There's too much public ambivalence and hesitation for it to be wise to say that there is a pro-life majority. But it is pretty clear that McCain is closer to the policy preferences of the median voter than Obama is. Yes, McCain wants to overturn Roe, which is unpopular. But he wants to move slowly toward a ban on abortion with exceptions for rape, incest, and threats to the mother's life, which is a mainstream and by some measures a majority position.