In Iowa, the Republican presidential contenders tried to outdo one another in attacking reproductive rights as they sought the support of caucusgoers from the religious right. In New Hampshire, where voters are less socially conservative, the candidates have focused more on economic issues.

But the message from Iowa was crystal clear: Mitt Romney, Rick Santorum, Ron Paul, Jon Huntsman Jr., Newt Gingrich and Rick Perry all stand ready to restrict a woman’s right to make her own childbearing decisions and deny essential health care to millions of women.

The Republican field is united in its determination to overturn Roe v. Wade; to appoint Supreme Court justices supportive of that goal; and to end government payments to Planned Parenthood for family planning services, cancer screening and other vital health services provided to low-income women. The candidates also want to reinstate the global gag rule that barred family planning groups abroad receiving federal money from even talking about abortion.

There are a few differences among the candidates. Only Mr. Gingrich has called for punishing judges who make abortion rulings not to his liking. Mr. Romney and Mr. Huntsman refused to sign the Susan B. Anthony pledge to appoint antiabortion cabinet members, among other things. Mr. Huntsman opposed the “personhood” initiative in Mississippi that would have given human fertilized eggs the legal rights and protections that apply to people, and outlawed abortion as well as some of the most widely used forms of contraception and in vitro fertilization. Mississippi voters resoundingly rejected the measure in November as going too far.