ABC News has announced that once Diane Sawyer moves in to the "World News" anchor chair following Charlie Gibson's retirement next year, "This Week" host George Stephanopoulos will be first in line subbing in for Sawyer when she's off. Politico's Mike Allen reports:

"As Diane Sawyer prepares to assume her new role at 'World News,' George Stephanopoulos is also expanding his duties," a network official said. "It's just been established that George will be Diane’s primary substitute on 'World News.' In addition, he will also be at her side on set for all major ABC News special events coverage."

Stephanopoulos has anchored "World News" news in the past. Recently, he filled in for Gibson while Gibson was on vacation following his retirement announcement.