Seventeen months after leaving office, former US President Donald Trump delivered on a campaign promise when the conservative US Supreme Court majority he cemented overturned the 1973 Roe v Wade ruling that legalised abortion nationwide.

Today's ruling represents a victory long in the making for a well-organised and generously funded conservative movement to push America's courts rightward, aided by legal activists and deft political manoeuvring by top Senate Republican Mitch McConnell.

Mr Trump, during his four years as president, appointed three justices - Neil Gorsuch in 2017, Brett Kavanaugh in 2018 and Amy Coney Barrett in 2020 - giving a court that was ideologically deadlocked with four liberals and four conservatives when he took office a solid 6-3 conservative majority by the time he left.

All three were in the majority in the decision to overturn Roe.

The month before being elected in November 2016, the Republican businessman-turned-politician, Mr Trump promised during a debate with his Democratic opponent Hillary Clinton to appoint justices who would overturn the Roe decision.

"Well, if we put another two or perhaps three justices on, that ... will happen automatically in my opinion because I am putting pro-life justices on the court," Mr Trump said at the time.

Mr Trump's pitch appealed to conservative Christian voters, who became a key constituency during his presidency.

Donald Trump speaks at the 47th March For Life rally

Mr Trump in 2020 also became the first US president to attend the March for Life in Washington, which is staged annually by abortion opponents around the anniversary of the Roe decision.

"Unborn children have never had a stronger defender in the White House," Mr mump told rally participants as he specifically touted his Supreme Court appointments.

Mr Trump has not announced whether he will run again for president in 2024.

Critics have sought to paint the Roe decision as poorly reasoned liberal judicial activism. Driven by vocal support from an anti-abortion movement spearheaded by conservative Christians, they pursued the goal of appointing judges hostile to abortion rights.

"The overturning of this case after the five decades of morass that Roe created is a major victory for constitutionalism and the rule of law," said Carrie Severino, president of the Judicial Crisis Network, a conservative legal group that has helped promote Republican judicial appointments.

"Roe v Wade was one of the greatest acts of judicial arrogance in Supreme Court history - and one of the catalysts for the birth and growth of the conservative legal movement," Ms Severino added.

'Break-glass moment'

For liberal legal advocates, the ruling represented a "break-glass moment," said Brian Fallon, executive director of legal advocacy group Demand Justice.

US Supreme Court

"Now the question is, will our side regroup and productively channel the public's outrage to confront a court that has been captured?" Mr Fallon asked.

The Supreme Court for decades had a majority of Republican appointees but until now lacked the five votes needed to overturn Roe. The last time it had been so close was in 1992 in a case called Planned Parenthood of Southeastern Pennsylvania v Casey.

Conservative activists were disappointed by the 5-4 ruling that reaffirmed the central holding of Roe recognising a woman's right to obtain an abortion under the US Constitution.

Three Republican appointees - Justices Sandra Day O'Connor, Anthony Kennedy and David Souter - worked behind the scenes on a compromise that carried the day.

It was later revealed that Mr Kennedy initially had supported overturning Roe but changed his mind. Mr Trump appointed Mr Kavanaugh to replace Mr Kennedy, who retired in 2018.

Mitch McConnell

Mr Trump and Mr McConnell - who have an icy relationship - were critical in engineering the demise of Roe. Mr McConnell, as Senate majority leader, in 2016 blocked Democratic President Barack Obama from appointing a justice to the court in the last year of his term after conservative Justice Antonin Scalia died.

Mr Obama's nominee would have given the court a 5-4 liberal majority.

Mr McConnell's action meant that Mr Trump was able to replace Mr Scalia with fellow conservative Mr Gorsuch.

Mr McConnell shepherded Mr Kavanaugh to Senate confirmation in 2018 after a contentious confirmation process in which the nominee denied sexual misconduct. Mr McConnell then moved rapidly with Senate confirmation of Ms Barrett a week before the 2020 election in which Mr Trump was defeated.

Amy Coney Barrett

Ms Barrett, a devout Roman Catholic and former legal scholar, previously had signalled support for overturning Roe.

Reliable conservatives

Since the Casey ruling, Republican presidents have chosen a stream of reliably conservative nominees nurtured and promoted by connections to the influential Federalist Society.

A key figure in that effort has been Leonard Leo, who has had a lengthy career at the conservative legal group and has advised Republican presidents in picking judicial nominees.

Mr Leo helped compile a list of potential Supreme Court nominees that Mr Trump touted as a candidate before the 2016 election in a bid to attract conservative voters. Mr Leo did not respond to messages seeking comment for this story.

Conservative advocacy groups including the Judicial Confirmation Network have helped promote and defend conservative judicial nominees. Anti-abortion organisations also have staunchly backed Republican judicial nominees.

"This victory represents proof of concept for the pro-life movement's involvement in campaigns and elections and will spur more pro-life political activism in the years ahead," said Mallory Carroll, a spokeswoman for one of those groups, Susan B. Anthony Pro-Life America.