A leading Republican senator said Sunday that he would block Senate confirmations of President Obama's nominees to lead the C.I.A. and the Department of Defense unless he was given more information on the attack on the United States compound in Benghazi, Libya, last year.
Senator Lindsey Graham of South Carolina, a vocal critic of the administration's handling of the attack, said he would use a Senate custom known as a hold to stall the nominations of John O. Brennan as C.I.A. director and former Senator Chuck Hagel as Pentagon chief until the White House gave him a full description of Mr. Obama's actions during the attack on Sept. 11.
"What did he do that night?" Mr. Graham asked during an appearance on CBS's "Face the Nation," suggesting that the president could have intervened to manage the crisis personally.
"That's not unfair," Mr. Graham added. "The families need to know."
Ambassador J. Christopher Stevens and three other Americans were killed when heavily armed Islamic extremist militants stormed and burned the compound.
The White House responded to Mr. Graham's threat early Sunday evening.
"We believe the Senate should act swiftly to confirm John Brennan and Senator Hagel," said Tommy Vietor, a spokesman for the National Security Council. "These are critical national security positions, and individual members shouldn't play politics with their nominations."
A hold is an informal measure by which any senator may prevent a vote without having to provide a specific reason or even identify who he or she is. But it can be overridden by a vote of 60 senators.
Senator Jack Reed, Democrat of Rhode Island, also on "Face the Nation," called Mr. Graham's threat "unprecedented and unwarranted." He added, "I think it is an overreaction that is not going to serve the best interests of going forward, of the national security of the United States."
Mr. Graham cited Democratic efforts in 2005 to hold up the confirmation of John R. Bolton, President George W. Bush's nominee as ambassador to the United Nations, as a precedent for his threatened hold.
This article originally appeared in The New York Times.