REUTERS - President Barack Obama will nominate a Supreme Court justice "in due time" after the death of Justice Antonin Scalia created a vacancy, the president said late Saturday, citing his and the Senate's duty to do so.

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.

Open gallery view Supreme Court Justice Antonin Scalia testifies before a House Judiciary Commercial and Administrative Law Subcommittee hearing on Capitol Hill in Washington, in this file photo taken May 20, 2010.

Obama paid tribute to Scalia's legacy on the bench in brief remarks to reporters, but did not give any indication about who he would nominate to replace him, saying he plans to fulfill his constitutional responsibility to nominate a Supreme Court justice to fill Scalia's place.

The death of the 79-year-old conservative justice, announced by Chief Justice John Roberts, promises to provoke a major confrontation between Obama, a Democrat, and the Republican-controlled Senate over who will replace Scalia later this year.

The prospect of such a battle drew swift and furious comment from candidates vying to be elected president in November.

The U.S. president has the job of nominating justices, and the Senate has the job of confirming. Senate Majority Leader Mitch McConnell, whose Republicans control the Senate, issued a statement saying the vacancy should not be filled until Obama's successor takes office next January so that voters can have a say in the selection.

In California for a summit of leaders from Southeast Asia, Obama pledged to tap a replacement for Scalia and said he was confident the Senate would have "plenty of time" to review and vote on the nomination.

"I plan to fulfill my Constitutional responsibilities to nominate a successor in due time," said Obama, who has the opportunity to become the first president to appoint three justices since Republican Ronald Reagan, who appointed Scalia in 1986. Obama did not indicate who he would nominate.

Another Obama nominee has the potential to swing the court in a more liberal direction, making this particular slot the most contentious in modern politics. The last time a Senate of one party confirmed the choice of the opposite party during an election year was in 1988, when Justice Anthony Kennedy, another Reagan appointee, was elevated to the high court.

Democratic presidential candidate Hillary Clinton urged Obama to nominate Scalia's replacement despite McConnell's threat.

"The Republicans in the Senate and on the campaign trail who are calling for Justice Scalia's seat to remain vacant dishonor our Constitution," Clinton said in a statement. "The Senate has a constitutional responsibility here that it cannot abdicate for partisan political reasons."

Republican presidential candidates Ben Carson, a retired neurosurgeon, and Ted Cruz, a U.S. senator from Texas, earlier had called on the president to leave the seat vacant until the next administration.

"Justice Scalia was an American hero," Cruz, a former Supreme Court law clerk, wrote on Twitter. "We owe it to him, & the Nation, for the Senate to ensure that the next President names his replacement."

Senator Charles Grassley of Iowa, who chairs the Senate committee that would vet a court nominee, also called on the White House to wait for the next president.

Democrats would likely be pleased to see Obama name a replacement, which would tip the balance of the nine-member court in favor of liberals after several years favoring conservatives by a 5-4 majority.

Despite the court's conservative credentials, Republicans have been highly critical, telling voters that a Republican president is needed to name jurists who will overturn such decisions as Roe vs Wade in 1973 legalizing abortion and one in 2015 legalizing same-sex marriage along with two decisions upholding aspects of Obama's 2010 signature healthcare law.

"The next president must nominate a justice who will continue Justice Scalia's unwavering belief in the founding principles that we hold dear," U.S. Senator Marco Rubio of Florida said in a statement.

The looming political battle is almost certain to come up when six of the Republican presidential candidates participate in a televised debate Saturday evening in South Carolina, which holds its Republican nominating contest on Feb. 20.

Race to replacement

Appointed to the top U.S. court in 1986 by President Ronald Reagan, Scalia was known for his strident conservative views and theatrical flair in the courtroom.

Scalia's replacement would be Obama's third appointment to the nine-justice court, which is set to decide its first major abortion case in nearly 10 years as well as key cases on voting rights, affirmative action and immigration.

Waiting for the next president to make a nomination would leave Scalia's seat empty for at least 11 months, an unprecedented gap in recent decades.

Obama's first two appointments to the court, liberals Sonia Sotomayor in 2009 and Elena Kagan in 2010, both experienced relatively smooth confirmation hearings in the Senate, which was then controlled by Democrats.

With Republicans now in charge of the Senate and keen to exert their influence over the process, 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.

Among those mentioned within legal circles as potential nominees are Sri Srinivasan, an Indian-American judge who has served on the U.S. Court of Appeals for the District of Columbia Circuit since May 2013, and Jacqueline Nguyen, a Vietnamese-American who has been a judge on the San Francisco-based 9th U.S. Circuit Court of Appeals since May 2012.

Paul Watford, a black judge on the 9th U.S. Circuit Court of Appeals who was appointed in May 2012, and Jane Kelly, a white woman and former public defender who has served on the St. Louis, Missouri-based 8th U.S. Circuit Court of Appeals since April 2013, also have been touted as possible nominees.

It has been nearly 50 years since political wrangling between a president and Senate pushed a Supreme Court nomination into the next administration.

In 1968, Chief Justice Earl Warren made clear his intention to resign and Democratic President Lyndon Johnson sought to elevate then-Associate Justice Abe Fortas, who had been a close confidant. Senate Republicans fought the nomination, claiming "cronyism," and Johnson withdrew it. The appointment fell to his successor, Republican Richard Nixon.