Democrats called the retirement of Justice Anthony Kennedy the 'most important vacancy in at least a generation'
Donald Trump has said the search will 'begin immediately' for a new US Supreme Court judge, in a political battle that could reshape the court for decades to come.
Yesterday, Justice Anthony Kennedy announced he will retire at the end of July, leaving a seat vacant.
Justice Kennedy - who was nominated for the highest court in the US by Ronald Reagan in 1988 - said the role has been "the greatest honour and privilege".
His replacement will now be nominated by President Trump, before being approved by Congress - offering Republicans an opportunity to swing the balance of the court to the right.
The retiring judge is considered a 'swing vote' in the nine-judge court - seen as conservative on issues such as gun control and voting rights, but liberal in areas such as gay rights and abortion.
With the court otherwise largely divided across ideological lines, a conservative nominee would see the balance shift to the right - which could have major consequences for decisions on a range of divisive social issues.
Supreme Court judges in the US are typically appointed for life, meaning Justice Kennedy's replacement could potentially serve for decades to come.
Vacant seats in the court have become a major political battleground in the US in recent years.
The death of Antonin Scalia in 2016 provoked a heated political battle, after Republicans refused to grant a hearing to then President Barack Obama's nominee until after the general election.
The empty seat was ultimately taken last year by conservative judge Neil Gorsuch, who was nominated by President Trump.
Republican Senate leader Mitch McConnell - who in 2016 insisted members of the public should have a say on Antonin Scalia's replacement through the general election - yesterday said a vote would be held on Justice Kennedy's replacement in the autumn, ahead of the mid-term elections in November.
The elections will see Democrats battling to retake control of both the House of Representatives and Senate, while Republicans will be looking to strengthen their existing majorities.
Yesterday, Mr McConnell said: "Senators will have the opportunity to meet with President Trump's nominee, examine his or her qualifications, and debate the nomination."
Republicans currently have a narrow majority of 51 seats to 49 in the Senate - limiting the opportunity for Democrats to obstruct the eventual nominee, after Republicans changed the voting rules to ensure Neil Gorsuch's confirmation with a simple majority.
Speaking yesterday, Democratic leader in the Senate Chuck Schumer called the vacancy 'the most important for this country in at least a generation'.
In a series of tweets, he wrote: "Nothing less than the fate of our health care system, reproductive rights for women, and countless other protections for middle-class Americans are at stake.
"People from all across America should realize that their rights and opportunities are threatened and should make their voices heard loudly, clearly, and consistently."
He also highlighted Republican politicians commenting on the 2016 vacancy, insisting an election was necessary before a hearing.
In 2016, Senate Republicans said that the American people deserve an opportunity to speak on Supreme Court nominees.— Chuck Schumer (@SenSchumer) June 27, 2018
Now that Justice Kennedy is retiring and @realDonaldTrump is president, will they silence them? pic.twitter.com/nT0wtgET6O
President Trump, meanwhile, paid tribute to the retiring judge - and stated the search would begin immediately for someone to fill the vacant seat.