President Joe Biden called on American voters Tuesday to defend the "fundamental" right to abortion after a leaked draft suggested the Supreme Court is poised to strike down the longstanding decision protecting a woman's right to terminate a pregnancy.
The opinion by the court's conservative majority hit Washington like a thunderclap late Monday, setting up a potentially historic turning point on a hot-button issue that is now certain to dominate November's midterm elections.
If the draft is made official -- which could happen within months -- it would shred half a century of constitutional protections for abortion rights, and give free rein to Republican-controlled states which are already leading an all-out push to curtail the procedure.
Biden's Democrats stand broadly united in support of abortion rights -- and rallied immediately in defence of the watershed 1973 Roe v. Wade decision.
While he cautioned the draft had not been verified, Biden said US voters will have to step up in defense of the right if the Supreme Court moves ahead.
"I believe that a woman's right to choose is fundamental, Roe has been the law of the land for almost fifty years, and basic fairness and the stability of our law demand that it not be overturned," the US leader said in a statement.
If the draft proves authentic, "it will fall on voters to elect" officials who back abortion rights in the coming midterm elections, he said, vowing to work to pass legislation in Congress that codifies Roe v. Wade.
- 'Roe v. Wade is going to go!' -
Crowds of protesters from both camps descended on the Supreme Court building in Washington in the wake of Monday's leak.
On Tuesday morning, two opposing groups -- small but vocal -- stood shouting chants at each other, with anti-abortion activists yelling "Abortion is violence. Abortion is oppression" and "Hey Hey Ho Ho Roe v. Wade is going to go!"
In Roe v. Wade, the nation's highest court held that access to abortion is a constitutional right.
In a subsequent 1992 ruling, Planned Parenthood v. Casey, the court guaranteed a woman's right to an abortion until the fetus is viable outside the womb, which is typically around 22 to 24 weeks of gestation.
Most developed countries allow abortions on request up to a gestational limit, most often 12 weeks.
Roe v. Wade makes the United States one of a handful of nations to allow the procedure without restriction beyond 20 weeks of pregnancy -- although many others allow it past that point for specific reasons.
Reproductive rights have been under attack in many parts of the United States as Republican-led states move to tighten restrictions, with some seeking to ban all abortions after six weeks, before many women know they are pregnant.
In December, hearing oral arguments about a Mississippi law that would ban most abortions after 15 weeks, the Supreme Court appeared inclined to not only uphold that law but to toss out Roe v. Wade.
Overturning the ruling would spell a massive victory for generations of Republicans who have fought tooth and nail to curb abortion rights, and would effectively leave the nation's 50 individual states to determine whether to protect or outlaw the procedure.
Striking it down "would be an answer to prayer," House Republican Jackie Walorski tweeted following news of the leak.
- 'Wrong from the start' -
The draft opinion was written by Justice Samuel Alito and according to news outlet Politico has been circulating since February inside the court -- dominated 6-3 by conservatives following the nomination of three justices by former president Donald Trump.
Politico stressed the document it obtained is a draft and justices do sometimes change their votes before a final ruling.
Such a leak while a case is still pending is an extraordinary breach of Supreme Court custom, and Republicans have demanded an investigation into how the draft was made public.
The 98-page draft majority opinion calls Roe v. Wade decision enshrining the right to abortion "egregiously wrong from the start."
"We hold that Roe and Casey must be overruled," Alito writes in the document, labeled as the "Opinion of the Court" and published on Politico's website.
"It is time to heed the Constitution and return the issue of abortion to the people's elected representatives."
The Guttmacher Institute, a pro-choice research group, has said 26 states are "certain or likely" to ban abortion if Roe v. Wade is overturned.
Democratic governors of several states including California, New Mexico and Michigan swiftly announced plans to enshrine abortion rights into law even if the court overturns Roe, with California Governor Gavin Newsom tweeting: "Women will remain protected here."