U.S. Supreme Court Justice Antonin Scalia, the longest-serving justice on the high court, is dead.
Scalia died in his sleep of natural causes at Cibolo Creek Ranch, a resort in southwest Texas.
The conservative Scalia was 79 years old. He was appointed to the high court by President Ronald Reagan in 1986.
The White House says President Barack Obama has sent his condolences to Scalia's family and plans to make a more extensive statement later Saturday.
Chief Justice John Roberts, in confirming Scalia's death, called him an "extraordinary individual and jurist, admired and treasured by his colleagues."
Texas Gov. Gregg Abbott, who first announced Scalia's death, called him "an unwavering defender of the written Constitution and the rule of law...a solid rock who turned away so many attempts to depart from and distort the Constitution."
There are nine justices on the Supreme Court. It will be up to the president to nominate Scalia's replacement, who will need to be confirmed by the Senate. But an eight-member court can also decide cases.
U.S. Senate Majority Leader Mitch McConnell, a Republican, immediately voiced opposition to President Obama nominating a successor.
"The American people should have a voice in the selection of their next Supreme Court justice. Therefore, this vacancy should not be filled until we have a new president," McConnell said said Saturday.
Obama would almost certainly nominate a liberal to the court. McConnell is banking on a Republican winning the presidency in November and naming a conservative.
With Scalia, the conservatives on the court enjoyed a slim 5-4 majority, although Justice Anthony Kennedy occasionally voted with his more liberal colleagues, most notably on the recent case they made gay marriage legal in the U.S.
Democratic Senate Minority Leader Rarry Reid said Obama "can and should send the Senate a nominee right away."
Mr, Obama intends to nominate a new Supreme Court justice.