Rousing Diane Sawyer is one thing. But waking up a somnolent morning show is another matter entirely. By appointing Sawyer and Gibson, who hosted ““GMA’’ for more than a decade before moving on to ““20/20’’ last year, ABC is hoping to stabilize a franchise that’s been in free fall. Once the top morning show, ““GMA’’ lost its lead to NBC’s ““Today’’ in 1995, and has seen its audience drop off 16 percent in the past year. Two weeks ago perennial bottom-dweller ““CBS This Morning’’ beat ““GMA’’ in the ratings for the first time in 20 years. ““The program has dwindled in importance and in viewership,’’ says ABC News president David Westin. ““We needed a dramatic move.’’ Convincing Sawyer, who certainly doesn’t need the additional work, and Gibson, who’s been there and done that, to take the helm couldn’t have been easy, could it? ““We had several discussions, but I wouldn’t say it was difficult,’’ says Westin. ““In the end both of them said, “If this is what you really need me to do, then I’ll do it’.''

The installation of Sawyer and Gibson, which is expected to last several months, will help steady the program while changes are introduced and a fresh anchor team is groomed. Former hosts Kevin Newman, who’s moving to ““Nightline,’’ and Lisa McCree, who took over for popular stalwart Joan Lunden in 1997, never had much chemistry and lasted only seven months together. ““We want to produce a warm program that is also smart, and that involves more of a family of contributors,’’ Westin says. This fall the show will move into a new glass-walled studio in Times Square. Tapping Sawyer and Gibson also suggests that ABC’s news division is serious about the show, a proposition that had been in doubt since ““GMA’s’’ 1995 transfer from the net’s entertainment operation.

Despite Sawyer’s star power and Gibson’s experience, nobody predicts a quick turnaround. ““I’m not particularly worried,’’ says Jeff Zucker, head of NBC’s ““Today.’’ ““I do welcome it because it will re-energize us as much as it re-energizes them.’’ Sawyer, too, has modest expectations. ““We don’t expect the ratings to change,’’ she says. ““I’m just here to help out. They have five cameras, so my first job is to figure out which camera I’ve got to look at.’’ Assuming, of course, she can keep her eyes open.