Another US state passed a law allowing abortion providers to be sued in civil court Wednesday, as conservatives across the country ramp up their effort to overturn long-held reproductive rights.

The bill in Idaho allows families of women who have had abortions -- and the father of the fetus -- to sue providers, taking enforcement out of the hands of the state, in a move modeled on a controversial Texas law.

Governor Brad Little, who signed the bill Wednesday, said he was an ardent supporter of the rights of "pre-born babies," but feared this approach rendered the law unconstitutional.

"While I support the pro-life policy in this legislation, I fear the novel civil enforcement mechanism will in short order be proven both unconstitutional and unwise," he wrote in a letter to the state legislature.

"Deputizing private citizens to levy hefty monetary fines on the exercise of a disfavored but judicially recognized constitutional right for the purpose of evading court review undermines our constitutional form of government and weakens our collective liberties."

As critics of the Texas law also pointed out, Little said framing legislation in this way rendered vulnerable rights that conservatives hold dear, such as the right to own guns.

Civil rights groups and the White House lambasted the Idaho law.

"Lawmakers openly touted this bill as a 'clever' way to undermine abortion access by evading judicial review," said Lauren Bramwell of the American Civil Liberties Union (ACLU).

The fight over abortion rights in the United States has never gone away, but as the Supreme Court looks set to revisit Roe v. Wade, local initiatives are reshaping access to the procedure The fight over abortion rights in the United States has never gone away, but as the Supreme Court looks set to revisit Roe v. Wade, local initiatives are reshaping access to the procedure Photo: GETTY IMAGES NORTH AMERICA via AFP / SCOTT OLSON

"It is irresponsible and politically motivated governing that will harm real people who deserve to decide for themselves what is best for them and their families, without political interference."

White House press secretary Jen Psaki said the Texas bill and copycat initiatives like the one in Idaho were a blatant attempt to undermine rights settled in the touchstone Roe v. Wade Supreme Court ruling that cemented a woman's right to abortion.

"This development is devastating for women in Idaho, as it will further impede women's access to health care, especially those on low incomes and living in rural communities," she said.

"Over the last six months, Texas' (law) has had profoundly negative effects, with women forced to travel hundreds of miles to access care, and clinics in neighboring states seeing a significant increase in demand."

Right-wing politicians have launched a full-frontal assault on abortion, a deeply divisive issue in the United States that is dear to their voters' hearts.

A total of 1,844 provisions relating to sexual and reproductive health and rights have been introduced in 46 US states during just the past two-and-a-half months, according to the Guttmacher Institute, which advocates for abortion rights.

Lawmakers in conservative Republican-led southern states have introduced bills tightening restrictions on abortion, while their counterparts in Democratic-ruled progressive states have submitted measures protecting a woman's right to choose.

The legislative frenzy comes as the Supreme Court, dominated by conservatives following the nomination of three justices by former president Donald Trump, looks poised to re-examine the 1973 Roe v. Wade ruling.