In an interview here after Sunday’s broadcast, Mr. Brokaw said that over the summer he had “advocated” within the executive suite of NBC News to modify the anchor duties of the MSNBC hosts Keith Olbermann and Chris Matthews on election night and on nights when there were presidential debates. Their expressions of strong political opinions from the MSNBC anchor desk has run counter to the more traditional role Mr. Brokaw played on “NBC Nightly News” for more than two decades. NBC said earlier this month that the two hosts would mostly relinquish their anchor duties to Mr. Gregory, while being present as analysts.

“Keith is an articulate guy who writes well and doesn’t make his arguments in a ‘So’s your old mother’ kind of way,” Mr. Brokaw said. “The mistake was to think he could fill both roles. The other mistake was to think he wouldn’t be tempted to use the anchor position to engage in commentary. That’s who he is.”

Mr. Brokaw said he had also conducted some shuttle diplomacy in recent weeks between NBC and the McCain campaign. His mission, he said, was to assure the candidate’s aides that  despite some negative on-air commentary by Mr. Olbermann in particular  Mr. McCain could still get a fair shake from NBC News. Mr. Brokaw said he had been told by a senior McCain aide, whom he did not name, that the campaign had been reluctant to accept an NBC representative as one of the moderators of the three presidential debates  until his name was invoked.

“One of the things I was told by this person was that they were so irritated, they said, ‘If it’s an NBC moderator, for any of these debates, we won’t go,’ ” Mr. Brokaw said. “My name came up, and they said, ‘Oh, hell, we have to do it, because it’s going to be Brokaw.’ ”

Mr. Brokaw will moderate the second debate, on Oct. 7, in Nashville.

Last week during the Clinton Global Initiative in New York, Mr. Brokaw said, he spoke briefly with Mr. McCain, who has not appeared on “Meet the Press” since Mr. Russert’s death. While Mr. Brokaw said he and the Republican nominee are not personal friends, he did say they are “friendly” and “always had a great relationship.”