Wisconsin Gov. Scott Walker is pushing legislation banning abortions after 20 weeks, which could bolster his appeal to conservatives in a 2016 run. (Nati Harnik/AP)

It came out of nowhere: an open letter from Wisconsin Gov. Scott Walker declaring his support for a ban on abortions once pregnancies reach 20 weeks.

The missive delighted antiabortion activists in the state — and set off a scramble in the State Capitol here because no such legislation had actually been introduced.

The restrictions, approved this week by the state Senate and likely to be passed by the Republican-dominated state Assembly, underscore the extent to which Walker — who has not yet announced his candidacy — is positioning himself to be the most fervent antiabortion candidate in the Republican field of presidential hopefuls.

The stance could help Walker win votes in conservative early-voting states, especially those with large numbers of evangelical Christian voters. But others are competing for those voters as well, including his main rivals of the moment, former Florida governor Jeb Bush and Sen. Marco Rubio (R-Fla.).

Walker is opposed to abortion in all cases — including when a pregnancy is the result of rape or incest — and he has received near-perfect ratings from antiabortion activist groups. As governor, Walker forced five health-care centers to close after stripping Planned Parenthood of funding, and he signed a law that required ultrasounds for women before they have an abortion.

Proponents of abortion rights have declared Walker’s record on the issue one of the most “dangerous” and “extreme” they have seen.

But Walker has an unexpected problem: Despite his record, he seemed to soften his rhetoric on abortion during his run for reelection last year, raising suspicions among some antiabortion activists that he wasn’t necessarily with them.

“I take him at his word, but it’s even more compelling to take him at his word when it’s coupled with action in his state,” said Marjorie Dannenfelser, president of the Susan B. Anthony List, a national group opposed to abortion.

Dannenfelser said that for the past year she has pressured potential 2016 contenders to publicly support a ban on abortions after 20 weeks, and she tracks their positions on her group’s Web site. Former Texas governor Rick Perry (R) signed a 20-week abortion ban into law in 2013, while Sen. Lindsey O. Graham (R-S.C.) introduced federal legislation that attracted statements of support from Bush, Rubio and five other Republicans who are declared or likely 2016 candidates.

Earlier this year, Dannenfelser criticized Walker for not joining in. In early March, Walker issued the “open letter on life” posted on the Susan B. Anthony List’s Web site; the declaration came two days after he struggled to answer questions about his abortion positions clearly on “Fox News Sunday.”

“I will sign that bill when it gets to my desk and support similar legislation on the federal level,” Walker wrote in the letter. “I was raised to believe in the sanctity of life and I will always fight to protect it.”

As written, the Wisconsin legislation would ban abortions after 20 weeks unless a “medical emergency” occurred. Doctors who performed abortions after that point could be charged with a felony, facing up to $10,000 in fines or 3 1/2 years in prison. The parents, including the father, could also sue for damages. There are no exceptions for pregnancies resulting from rape or incest.

Walker told local reporters last week that he would sign the legislation into law with or without that exception.

“I think for most people who are concerned about that, it’s in the initial months where they’re most concerned about it,” Walker said of pregnancies related to rape and incest.

That comment quickly prompted criticism.

“Really?” said state Sen. Lena C. Taylor, a Democrat from Milwaukee. “How does he know what goes on in the minds of pregnant women who have been raped or who have experienced incest, who are survivors? How does he know?”

Democrats have also criticized Walker for defending his state’s mandated ultrasounds by gushing about seeing his son’s first ultrasounds years ago. “It’s just a cool thing out there,” he said of such photos.

As a young lawmaker in the Wisconsin Assembly in the 1990s, Walker helped write and pass legislation that requires women seeking an abortion to wait 24 hours and that bans a seldom-used procedure known by opponents as “partial-birth abortion.” Walker unsuccessfully tried three times to pass legislation that would protect doctors, pharmacists and other health-care workers who refuse to engage in procedures that conflict with their religious beliefs, including performing an abortion, using stem cells or dispensing some birth-control drugs. He also tried unsuccessfully to require minors to obtain parental consent before having an abortion.

In campaign-style appearances in Iowa and South Carolina, Walker has bragged about stripping Planned Parenthood of state funding while governor. Planned Parenthood officials say the funding went to non-abortion services such as cancer screenings and providing birth control and that the cut forced them to close five health centers in rural areas that do not perform abortions.

When Walker ran for reelection last year, Democratic opponent Mary Burke slammed his record on women’s health issues. Walker avoided discussing abortion and declined to complete a Pro-Life Wisconsin survey, forfeiting the group’s endorsement. As he lagged in the polls, his campaign released an ad that defended the ultrasound law but also gave some the impression that he supported leaving abortion decisions to women and their doctors.

“He sees the polling that we see, and he knows that it’s not popular to say you want to ban abortion in Wisconsin,” said Nicole Safar, Planned Parenthood of Wisconsin’s policy director.

Now that Walker might compete for the Republican nomination, he is touting his record. A clear majority of Republicans are opposed to abortion in most cases and express support for a variety of restrictions, including bans after 20 weeks into a pregnancy. Evangelical Christians are among the most opposed, and they made up 57 percent of GOP caucus-goers in Iowa in 2012 and half of all GOP primary voters in states where exit polls are available.

Walker steps into less popular territory in espousing absolute opposition to abortion. For example, a large majority of Americans say a woman should be able to get an abortion if the pregnancy is a result of rape.

When asked last weekend why he opposes abortion in all cases, Walker simply stated that he’s pro-life — and then went after Democratic front-runner Hillary Rodham Clinton for favoring fewer restrictions on abortion.

“Which I think,” he said, “puts her squarely out of touch of where most Americans are at.”

Scott Clement contributed to this report.