Senator Lindsey Graham on Sunday stood by his threat to block all nominations by the Obama administration until Congress was granted access to all the survivors of the attack on the United States Mission in Benghazi, Libya, even as the news report on which Republicans based their latest demands was being retracted.

Mr. Graham, Republican of South Carolina, said on the CNN program “State of the Union” that he would not back away from his threat because he had been asking to talk to the witnesses of the attack on Sept. 11, 2012, for a long time without success.

“I’ve been trying for a year to get the interviews without holds, and you just can’t allow something this bad and this big of a national security failure for the administration to investigate itself,” he said.

CBS News plans to broadcast a rare correction Sunday to a recent “60 Minutes” program in which a security officer, Dylan Davies, recounted being at the mission on the night of the attack. It was later uncovered that his account on CBS News and in a newly published book differed from what he had told the F.B.I., casting doubt on his credibility.

After the “60 Minutes” report was broadcast, seeming to support claims that the mission was not adequately secured and that the attack was the result of a terrorist plot, some Republican senators renewed calls for the Obama administration to make survivors of the attack available to congressional investigators. Mr. Graham vowed to hold up President Obama’s nominations until the administration complied, citing the CBS News report to substantiate his demands.

Mr. Graham said he had not known of Mr. Davies until the “60 Minutes” report came out.

When asked how many witnesses would satisfy his request — with one having already testified in a closed hearing with members of the House and three former security officers set to testify next week, according to CNN — Mr. Graham said he wanted to question all five survivors, plus the Central Intelligence Agency officials with knowledge of what happened in Benghazi. He estimated that the total would be no more than 30 people.

“The State Department has thus far refused to allow anybody in Congress to talk to these five,” he said. “And we’re going to talk to them because they possess the best information about what happened at Benghazi, more than you and I know, and I want to find out what they know.”

The attack has been the subject of outrage among congressional Republicans, many of whom have accused the administration of failing to secure the diplomatic compound and of misleading the public about whether the attack had arisen spontaneously from a protest or from a planned terrorist effort. State Department officials, including then-Secretary of State Hillary Rodham Clinton, have testified before Congress, and an independent inquiry determined there were serious security failures.

Mr. Davies — who gave his public account under the pseudonym Morgan Jones — told CBS News that on the night of the attack, he visited the hospital where he saw the body of J. Christopher Stevens, the American ambassador who was killed, as well as the compound, where he fought off an attacker.

But that version of events contradicted his account to the Federal Bureau of Investigation, in which he said he did not arrive on the scene until the next morning, which matched the incident report completed by his security firm. Faced with that revelation, CBS News said that Mr. Davies had misled the network and that it would issue a retraction on Sunday night.