(Reuters) - Mississippi lawmakers have approved a measure banning abortion after 15 weeks of gestation, moving the state a step closer to enacting the United States’ most restrictive abortion law, the lieutenant governor said on Tuesday.

The legislation, approved by the Senate in a 35-14 vote and similar to a bill previously passed by the House of Representatives, is seen by abortion rights advocates as a potential test of the legal limits of abortion.

Current state law bans abortion at 20 weeks after conception. House Bill 1510 will return to the House to reconcile differences between the two Republican-controlled chambers’ versions, Republican Lieutenant Governor Tate Reeves said in a statement.

“Mississippians are committed to protecting the lives of unborn children, and this law will be a major step in accomplishing that goal,” he said.

Republican Governor Phil Bryant has pledged to approve the measure if lawmakers send it to his desk.

Abortion rights advocates said the measure targeted the state’s only abortion provider, the Jackson Women’s Health Organization. It provides abortions for up to 16 weeks after conception.

“There is no question that H.B. 1510 is a strategic move by the anti-choice movement to make Mississippi the first state where legal abortion is no longer accessible,” NARAL Pro-Choice America National Communications Director Kaylie Hanson Long said in a statement.

State Representative Becky Currie, a Republican, who introduced the measure, did not respond to requests for comment. A similar measure banning abortion 15 weeks after conception also has been introduced in the Louisiana state Senate.

The Mississippi bill includes an exception in the case of severe fetal abnormality or a medical emergency.

Leslie McGorman, deputy policy director at Pro-Choice America, an abortion rights group, said abortion rights groups likely would mount a court challenge if the Mississippi measure became law, and anti-abortion organizations then could use the case to test the limits of abortion all the way to the U.S. Supreme Court.

The high court legalized abortion in its 1973 Roe v. Wade ruling. It has banned prohibiting abortion before the fetus is able to live outside the womb, usually seen at about 20 weeks of gestation.

Seventeen states ban abortion at about 20 weeks after fertilization or its equivalent of 22 weeks after the woman’s last menstrual period, according to the Guttmacher Institute, which opposes abortion limits.

The Guttmacher Institute has said about 926,200 U.S. abortions were performed in 2014, down 12 percent from 2011.

A 2017 Gallup poll showed 49 percent of Americans said they support abortion and 46 percent opposed it.