US President Barack Obama nominated Merrick Garland, a centrist judge, to the US Supreme Court to fill a vacancy created by the death of ultra conservative judge Antonin Scalia.
Garland currently serves as chief judge of the US Court of Appeals for the District of Columbia Circuit.
Obama made the choice after carefully considering the Republican opposition to a liberal judge and a stiff confirmation challenge he might face in a Republican dominated Senate.
The 65-year-old Garland is a former prosecutor who has won praise from both Republicans and Democrats.
The president set the ball rolling for an immediate confirmation hearing, dispatching Garland to the Capitol Hill to meet senior members of the Senate judicial committee.
The president said he hoped the Republicans in the Senate would give Garland, who hails from Chicago, a fair hearing.
Republicans have stuck to the stance that the nomination to the highest court should be done only by the next president and that they will block anyone proposed by outdoing president Obama.
But Obama said any move to block the nomination "will not only be an abdication of the Senate's constitutional duty, it will indicate a process for nominating and confirming judges that is beyond repair.
However, the Republicans reiterated their stance hours after Obama announced the nomination. "Any meeting with any nominee put forward by President Obama would only be a waste of the Senate's time," a Republican member of the judiciary committee, Mike Lee, said.
"The court has very ably dealt with temporary absences in the past and will do so again now," he added, according to the Guardian.