US President Donald Trump nominated Amy Coney Barrett, a favourite of social conservatives, to be the new Supreme Court justice.
Speaking by her side at the White House Rose Garden, Mr Trump described her as a “woman of unparalleled achievement”.
If confirmed by senators, Judge Barrett will replace liberal Justice Ruth Bader Ginsburg who died recently, aged 87. She would also be the fifth woman ever to serve on the court and would push its conservative majority to a commanding 6-3.
The nomination will spark a bitter confirmation fight in the Senate as November’s presidential election looms.
Trump’s fellow Republicans holding a 53-47 Senate majority, confirmation appears certain, although Democrats may try to make it as difficult as possible.
Announcing Judge Barrett as his nominee on Saturday, President Trump described her as a “stellar scholar and judge” with “unyielding loyalty to the constitution”.
“Today it is my honor to nominate one of our nation’s most brilliant and gifted legal minds to the Supreme Court,” Trump said.
Trump said Barrett would be the first mother of school-age children ever on the court. Along with her lawyer husband, her children, two of whom were adopted from Haiti, were in the audience.
Trump’s Democratic rival Joe Biden repeated his call for the appointment to be made by the winner of the Nov. 3 election.
“The Senate should not act on this vacancy until after the American people select their next president and the next Congress,” Biden said.
Like Trump’s two other appointees, Neil Gorsuch in 2017 and Brett Kavanaugh in 2018, Barrett is young enough that she could serve for decades in the lifetime job, leaving a lasting conservative imprint. Barrett is the youngest Supreme Court nominee since conservative Clarence Thomas was 43 in 1991.
Scalia, who died in 2016, was one of the most influential conservative justices in recent history. Barrett previously served as a clerk for Scalia on the high court and described him as her mentor, citing his “incalculable influence” on her life.
Judge Barrett has ruled in favour of President Trump’s hardline immigration policies and expressed views in favour of expansive gun rights.
Conservatives hope she will rule against the Affordable Care Act – a health insurance scheme introduced by President Trump’s Democratic predecessor Barack Obama.
Some 20 million Americans could lose their health coverage if the court overturns the legislation, also known as Obamacare.