But after announcing Gibson's retirement Wednesday, ABC News President David Westin rewarded Sawyer's forbearance by naming her to the network's top news post, saying she has "more than paid her dues and waited her turn appropriately."
"It was her time, in my judgment," Westin said.
After a decade of waking before dawn to host "Good Morning America," the 63-year-old Sawyer has finally secured the job on "World News" that colleagues say she has long sought, though she was careful not to lobby for it directly.
It's the capstone of a career for Sawyer, who got her start as a local television reporter in Louisville, Ky., and worked as an aide to President Richard Nixon before joining CBS News, where she served as the first female correspondent of "60 Minutes." She joined ABC in 1989 as co-anchor of "Primetime Live," a post she continued to hold after being recruited by Westin to help shore up a struggling "GMA" in 1999 as co-host with Gibson.
The ascension of Sawyer cements her standing as ABC's top news personality and means that for the first time, there will be two women anchoring the networks' flagship evening news programs. But as she joins NBC's Brian Williams and CBS' Katie Couric in the top echelon of broadcast news, Sawyer faces the challenge of making her mark in a genre that has been in a steady decline. An average of 22.6 million viewers tuned in to watch the three newscasts so far this season, down from 28.5 million 10 years ago.
And "World News" faces its own challenge. With Gibson at the helm, the ABC program nearly matched top-rated "NBC Nightly News" during the 2006-07 season but has since remained firmly in second place. This season, "World News" has drawn an average of 812,000 fewer viewers than NBC.
"I am frustrated in being No. 2," said Jon Banner, executive producer of "World News," who said he had tried to talk Gibson out of leaving. "I think we're blessed having someone of Diane's stature and experience coming here. So we're ready to continue to fight."
As Gibson's longtime partner during major news events, Sawyer is no stranger to ABC's evening news viewers. But after such a long stay in morning television, she must make a transition to the more staid evening newscast format, a genre that Couric tried without success to reinvent.
"That there was so much emphasis on Katie as the first woman will lessen the scrutiny on Diane, but it still will be there, because Diane has become associated with softer human interest features," said Judy Muller, a former ABC correspondent who now teaches journalism at USC. "Will she have that credibility for anchoring the big events of our lives? If there's one criticism out there, it's that she veers into sentimentality more than other anchors might."
ABC News executives emphasized Sawyer's hard news background, first as a State Department correspondent for CBS and continuing with primetime documentaries on North Korea and children in poverty.
Westin noted that she has interviewed every president since George H.W. Bush and has been a pivotal part of the network's political coverage.
"She's very accomplished and she will bring her own sensibility to the program and put her own stamp on it, the way Charlie did and the way Peter did, always consistent with the underlying DNA of 'World News,' which does not change," he said.
The network did not make Sawyer available for an interview, but she said in a statement that "there is no one like Charlie Gibson and it is an enormous honor to be asked to join the terrific broadcast he and the great team of journalists have built at 'World News.' "
Inside the news division, the timing of Wednesday's announcement was met with some surprise, particularly since it left open the question of what will happen on "GMA," the news division's most profitable program, when Sawyer replaces Gibson in January.
ABC News finds itself in a recurring predicament: how to shore up "World News" without damaging "GMA." Even though it gets trumped by NBC's "Today," the morning show is still its most valuable franchise.
The loss of Sawyer, who is known for her intense focus on details such as video selection, will up-end the program dramatically.
Westin said he does not know who will replace Sawyer, but he has no plans to change the remaining team of co-host Robin Roberts, news anchor Chris Cuomo or weatherman Sam Champion.
The timing of Gibson's departure may have come as a surprise, but it was no secret that he had put off retirement to help steady the news division after the back-to-back traumas of Jennings' death from lung cancer in 2005 and Woodruff's serious injury while on assignment in Iraq.