The death of conservative US Supreme Court Justice Antonin Scalia has set up a major political showdown between President Barack Obama and the Republican-controlled Senate over who will replace him just months before a presidential election.
Obama called Scalia, 79, a "larger-than-life presence" on the court and said he would nominate a successor.
"I plan to fulfill my constitutional responsibility to appoint a successor in due time and there will be plenty of time for me to do so and for the Senate to give that person a fair hearing and timely vote," Obama said.
A number of leading Republicans, including Senate Majority Leader Mitch McConnell and Senate Judiciary Committee Chairman Chuck Grassley, opposed Obama's intention to nominate a new justice.
The looming political battle came up at the outset of the Republican presidential debate in South Carolina when frontrunner Donald Trump was asked about replacing Scalia. The state holds its Republican nominating contest on February 20.
"Justice Scalia was an American hero. We owe it to him, and the nation, for the Senate to ensure that the next president names his replacement," Senator Ted Cruz of Texas, a Republican White House hopeful, said on Twitter earlier on Saturday.
Signalling that Obama would face a stiff battle to win confirmation of a nominee before he leaves the White House in January, McConnell said in a statement that the vacancy on the high court "should not be filled until we have a new president".
Obama could tilt the balance of the nation's highest court, which now consists of four conservatives and four liberals, if he tries to and is successful in pushing his nominee through the confirmation process.
"Unless he (Obama) can find a consensus choice, the next president will pick the replacement for Justice Scalia," said Senator Lindsey Graham, a Republican who also sits on the Senate Judiciary Committee.
Obama is likely to be forced into picking a moderate with little or no history of advocating for liberal causes.
Other factors the White House is likely to consider is whether to nominate a woman or a member of a minority group, or someone who fits into both categories.
It has been nearly 50 years since political wrangling between a president and Senate pushed a Supreme Court nomination into the next administration.