COLUMBUS, Ohio - Gov. Mike DeWine signed one of the nation's most restrictive abortion bans into law Thursday afternoon and opponents have already pledged to take him to court.

DeWine, a Republican, said government’s role should be to protect life from beginning to end.

“The signing of this bill today is consistent with that respect for life and the imperative to protect those who cannot protect themselves,” DeWine said moments before signing the bill at the Ohio Statehouse, flanked by GOP legislative leaders and abortion opponents.

The American Civil Liberties Union of Ohio has already promised to sue over the legislation, which would ban abortions after a fetal heartbeat is detected and prosecute doctors who perform them anyway. A fetal heartbeat can be detected as early as six weeks into a woman's pregnancy, which can be before a woman finds out she's pregnant.

The "heartbeat bill" passed the GOP-controlled Legislature on Wednesday amid protests from advocates of abortion access. DeWine signed the bill at 3:30 p.m. Thursday, making Ohio the sixth state to enact the ban.

Under the bill, doctors would face a fifth-degree felony punishable by up to a year in prison for performing an abortion after detecting a heartbeat. The bill has an exception to save the life of the woman but no exception for rape or incest – in line with current state law.

Republican legislators rejected Democratic amendments to expand eligibility for maternal health services and provide access to paid maternity leave.

Ohio Democratic Party Chairman David Pepper said the bill takes Ohio in the wrong direction.

"A woman should have the ability to make her own personal decision about whether or not to become a parent, and no politician should interfere in that decision," Pepper said in a statement. "This bill is a disgrace, and it will endanger women’s lives in Ohio."

DeWine said his administration is committed to helping pregnant women and that his budget puts "a lot of focus on making sure that women who are in difficult circumstances have the help they need."

The legislation was crafted in Ohio, but it has gained momentum nationwide. Ohio is one of four states to pass the abortion ban in 2019 alone. A similar bill sits on Georgia Gov. Brian Kemp's desk.

Former Gov. John Kasich vetoed the abortion ban twice, concerned about the legal bill taxpayers would foot.

"Pro-life Ohio thanks Governor DeWine for taking a courageous stand on behalf of unborn children with beating hearts,” said Mike Gonidakis, president of anti-abortion group Ohio Right to Life.

Legal challenges have blocked similar restrictions in other states. To date, all courts have found the legislation unconstitutional; some litigation is ongoing. The U.S. Supreme Court has declined to take up the issue so far.

"This legislation is blatantly unconstitutional and we will fight to the bitter end to ensure that this bill is permanently blocked," said Freda Levenson, ACLU of Ohio's legal director.

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'Heartbeat bill':Ohio lawmakers pass one of the nation's most restrictive abortion bans

DeWine, the former state attorney general, said Thursday that the bill's purpose is to be a vehicle for the court to revisit its landmark decision in Roe v. Wade.

“Taking this action really is in a time-honored tradition, a constitutional tradition of making a good faith argument for the modification or reversal of existing legal precedent,” DeWine said. "The United States Supreme Court will ultimately make a decision."

Follow Jessie Balmert on Twitter: @jbalmert