Wisconsin Republicans on Thursday announced plans to introduce a “Pain-Capable Unborn Child Protection Act,” a proposal that would ban abortion after 20 weeks‘ gestation based on the unsubstantiated belief that fetuses can feel pain at that point.

Gov. Scott Walker, a 2016 Republican presidential hopeful, said in March that he would sign such a bill if it came to his desk.

The claim that fetuses can feel pain after 20 weeks is based on research discredited by medical professionals, including the American Medical Association and the American Congress of Obstetricians and Gynecologists.

Wisconsin’s 20-week abortion ban bill is co-authored by three GOP representatives and one senator, who say the measure will protect the unborn.

“Viability is not the only compelling reason to preserve live,” state Rep. Jesse Kremer (R) said in a statement. “Simply put, the Pain-Capable Unborn Child Protection Act will preserve and protect Wisconsin’s innocent, unborn babies who can feel pain. The call to preserve precious, human life transcends party lines.”

Both chambers of the Wisconsin state legislature are majority Republican.

Ten states have instituted unconstitutional bans on abortion at 20 weeks based on the “fetal pain” hypothesis, according to the Guttmacher Institute. Twenty-one states have unconstitutional limits on abortion before the point of viability, usually understood to be 24 weeks.

Wisconsin Right to Life said last November that it would push a 20-week abortion ban this session.

Senate Minority Leader Jennifer Shilling (D-La Crosse) said Democratic lawmakers would fight the GOP’s proposed 20-week abortion ban.

“Abortions after 20 weeks are extremely rare and often result from extraordinary health complications that require doctors to consider every medical option available,” Shilling said in a statement. “This bill will jeopardize women’s safety and prevent health professionals from making life-saving medical decisions.”

Ninety-eight percent of abortions happen before the 21-week mark, according to the Guttmacher Institute.

Walker has always taken anti-choice stances, but until recently said he would ultimately support legislation leaving “the final decision” of whether to get an abortion “to a woman and her doctor.”

Walker said in a March interview with Fox News Sunday that a person’s choice to terminate a pregnancy is protected by the Supreme Court.

“Legally, that’s what it is under the guidelines that was provided from the Supreme Court,” he said.

But following pressure from conservative groups, and ahead of his 2016 presidential bid, Walker wrote an “open letter on life,” clarifying his position on abortion and the 20-week ban.

“As the Wisconsin legislature moves forward in the coming session, further protections for mother and child are likely to come to my desk in the form of a bill to prohibit abortions after 20 weeks,” he wrote. “I will sign that bill when it gets to my desk and support similar legislation on the federal level.”

“Pain-Capable Unborn Child Protection” acts have been introduced in a handful of states this year, including Ohio, South Carolina, Virginia, Maryland, and Oregon. West Virginia passed a 20-week abortion ban in March, after the GOP-dominated legislature overrode Republican Gov. Earl Ray Tomblin’s veto.