Gibson has decided to depart after serving three years as the face of ABC News, helping to stabilize a news division rocked by the death of longtime anchor Peter Jennings and then the serious wounding in Iraq of one of his successors, Bob Woodruff. 'It has not been an easy decision to make,' Gibson wrote in an e-mail to staff. 'This has been my professional home for almost 35 years. And I love this news department, and all who work in it, to the depths of my soul. 'The proudest part for me has been saying `... for all of us at ABC News ...,' since those words signify in my mind that I have been in a position to speak for an entire news department that I consider second to none,' he added. Gibson said he had intended to retire in 2007 but stayed on to help stabilize the news division. 'It was an honor to do so,' he wrote. '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.' 'Charlie and I have been talking about his decision for several weeks, and he has persuaded me that this is both what he wants and what is best for him,' ABC News President David Westin wrote in an e-mail to staff. 'I respect his decision, just as I respect the enormous contribution he has made to ABC News through the years. Most recently, he stepped in to lead `World News' after a difficult and turbulent time -- both for the broadcast and for ABC News over all. We suffered from the loss of Peter and then the severe injuries to Bob. Charlie came to the fore to keep us on the path of doing the first-rate journalism that had distinguished `World News' for many years. We owe him much for the leadership he gave us when we needed it most.' When Sawyer, a fixture on 'Good Morning America' for the last 10 years, takes the anchor chair of 'World News' in January, she will compete against NBC's Brian Williams and CBS' Katie Couric. It will mark the first time two women have served as anchors of evening newscasts. 'Diane Sawyer is the right person to succeed Charlie and build on what he has accomplished,' Westin wrote. 'She has an outstanding and varied career in television journalism, beginning with her role as a State Department correspondent and continuing at `60 Minutes,' `Primetime Live' and `Good Morning America.' She has interviewed every president since President George H.W. Bush up to and including President Obama. She has handled an array of breaking news special events, including on 9/11 and, most recently, the presidential election. 'Diane's presence will certainly be missed on `Good Morning America,' ' he added. 'But we are fortunate that both Charlie and Diane will remain with their current broadcasts for the next four months; we will be making further announcements well before any changes are made.' In a statement, Couric offered praise for her ABC competitors. 'Ever since my days as a desk assistant at ABC News, I've always admired Charlie's work,' she said. 'He's a talented reporter, a gifted communicator and a wonderful person. I wish him all the best. Diane is one of the hardest-working people I know and this new assignment is the latest achievement in an already accomplished and illustrious career. And as I did, I'm sure she'll quickly find that she doesn't miss that early morning alarm clock.' 