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.
People who know the 66-year-old anchor said he always saw himself as a transitional figure. It frustrated him that "World News" had lagged behind NBC, but he had little interest in blogging and other new media ventures.
In an e-mail to his staff, Gibson said "I love this news department, and all who work in it, to the depths of my soul. . . . The program is now operating at a very accelerated, but steady, cruising speed, and I think it is an opportune time for a transition -- both for the broadcast and for me. Life is dynamic; it is not static."
Sawyer's appointment to the "World News" anchor desk completes what has been a complicated dance between the longtime co-hosts when it comes to pursuing the evening news job. Sawyer was widely seen as wanting the job, but had been circumspect over the years about her interest in the post.
"She had pretty much always said, 'I'm interested, but I'm not sure it's right for me or I'd want to do it,' " Westin said. "And when the succession became necessary after Peter and Bob, she always said that Charlie was the right person to put in there, that she should not be considered in front of Charlie."
In an interview earlier this year, Sawyer dodged when asked if she wanted to succeed Gibson on "World News."
"You know, I feel the same way I've always felt: You never know until the moment about what you want to do next in this world," she said. "I've never been able to plan ahead and say, 'That's my aim, that's my goal,' because the thing you think may hold the most emotional and journalistic riches for you will turn out to be something that is not what you want to do at all."
Last Thursday, two days after Gibson told him he had decided to retire, Westin approached Sawyer again.
"She expressed a lot of questions and doubt," he said. Sawyer pressed him about whether he could persuade Gibson to stay on, then peppered him with questions about the evening news landscape.
For five days, she played her cards close to the vest. Finally, at 7 p.m. on Tuesday, she called the news president on his cellphone while he was visiting the 79th Street Boat Basin Cafe with his family.
"I'm willing to do it," she told him.