Abortion fights test public ambivalence. The absolutist voices have always dominated the abortion debate. But as it flares again in Congress and in legislatures across the country, the fight this time is heading into complicated political terrain, stirring the ambivalence that most Americans feel about the issue. In Texas, one of the most restrictive and closely watched abortion measures in the country appears headed for passage this week after Gov. Rick Perry (R) resurrected it by calling a special session of the legislature. On Wednesday, the state House voted 96 to 49 to approve the controversial antiabortion legislation that has prompted two special sessions. The bill bans abortions after 20 weeks of gestation and imposes new limits on abortion clinics, doctors and pills. The state Senate is expected to add its approval later this week. Sean Sullivan Expect differences to emerge in a group that has mostly refused to march in lockstep on a variety of other fronts. Libertarians have spent years trying to deal with the sliver of their movement that is focused on re-litigating the Civil War. Meanwhile, in North Carolina, another GOP governor, Pat McCrory, is threatening to veto a measure that contains some of the same provisions, saying he is concerned that its new regulations on abortion clinics might cross "a fine line between safety measures and restrictions." Fine lines are not something activists on either side often recognize. But four decades after the Supreme Court's landmark decision in Roe v. Wade, the views of most of Americans on abortion remain complex and conditional. While there are very well­ organized and very ideological pro-life and pro-choice groups, your average citizen is in neither of these groups. He or she is in the middle," said Tom W. Smith, head of the General Social Survey at the University of Chicago's National Opinion Research Center, who has been tracking public sentiment on abortion since 1972. Except in the first few years after Roe v. Wade made abortion legal, when public acceptance grew, sentiment around the issue has not moved much. Nor is there a large generational divide. That distinguishes abortion from other contentious social issues, such as same-sex marriage and marijuana legalization, where overall public opinion - led by the young - has shifted dramatically in favor of a more liberal position. For decades, polls have shown that most people want abortion to be available to women, at least in the early stages of pregnancy, when the vast majority occur. But Americans get increasingly uncomfortable with the procedure as a fetus gets closer to viability. In December, a Gallup poll found roughly six in 10 saying abortion should be legal in the first three months of pregnancy, but support dropped to 27 percent in the second trimester and to 14 percent in the third. Data just released by the National Opinion Research Center show that most Americans think the woman's decision to have an abortion is justified in some instances - rape (where 78 percent support abortion as an option), fetal deformity (77 percent) and serious danger to her health (87 percent), for example. But they do not support it when an abortion is sought because the woman believes she is too poor to have more children (a situation in which 45 percent say they approve of an abortion) or doesn't want to marry the father (42 percent).