The glass slipper finally fits Brian Williams, who on Tuesday was named to succeed Tom Brokaw as the anchor of the “NBC Nightly News” after the November 2004 elections.

Brokaw, 62, has headed the broadcast since 1983 as part of a longstanding triumvirate that also includes “CBS Evening News” anchor Dan Rather, 70, and “ABC World News Tonight” anchor Peter Jennings, 63. Rather, the senior partner, has been in “The Chair” since 1981, while Jennings took over World News in 1983.

Flanked by NBC’s top executives, Brokaw and Williams, 43, made the transition official at an early afternoon news conference in NBC’s historic Studio 8H in Manhattan.

Williams, who joined NBC News in 1993 and has been anchoring MSNBC cable’s “The News With Brian Williams” since 1996, praised Brokaw as “an enlarged American citizen” in times of crisis.

Anchoring a network evening newscast is “still a big position in this country,” Williams said. “And there’s no better example of that than what Tom has done as the public face of this news division.”

Brokaw said that he had considered stepping down earlier but was “re-energized in every conceivable way” by the Sept. 11 terrorist attacks and America’s response to them.

“This is one of the most challenging and complex stories that I have ever encountered,” Brokaw said. “It is rich and important and serious every day, and I can’t wait to get up in the morning and wade back into it.”

But reported efforts to lure Williams from NBC put pressure on Brokaw to set a firm departure date from “Nightly News.”

“I knew that obviously Brian had a lot of overtures from other networks. The last thing we wanted to do was lose him,” Brokaw said.

He settled on the end of the 2004 campaign as an apt time to pass the baton before remaining at NBC News in other capacities.

“You all know how much I love American politics,” Brokaw said. “I’d like to see one more presidential election.”

Williams, a former volunteer firefighter in his native New Jersey, will have an increased role on “Nightly News” during a two-and-half-year march to the program’s anchor post.

“We’re gonna get his boots muddy in the next two years in a lot of different places around the world,” Brokaw said.

Williams also will sub more frequently for Brokaw on “Nightly News” while continuing to anchor “The News With Brian Williams.” But on a yet-to-be-announced date, that program will leave MSNBC and air only on CNBC cable, which NBC also owns.

NBC News president Neal Shapiro said that Brokaw will “continue to be one of the busiest journalists in television news” after bequeathing “Nightly News” to Williams.

“It doesn’t mean I’m going to go sit in the anchorman’s rest home and take soft food,” Brokaw said.