Mr. Stephanopoulos will contribute to various programs, but at the outset he will appear most often as a political analyst on This Week, the Sunday morning news program with Cokie Roberts and Sam Donaldson as co-hosts. Eventually Mr. Stephanopoulos is expected to do some reporting as a correspondent, the network said.

The overnight transformation of George Stephanopoulos from partisan pitchman to television journalist highlights a disturbing phenomenon: the progressive collapse of the walls that traditionally separated news from propaganda. Self-respecting news organizations used to pride themselves on the sturdy barriers they maintained to guard against all kinds of partisan contamination....[Stephanopoulos’s] case shows how no one even bothers any longer to decontaminate a convert (like, say, Bill Moyers) by stretching out his passage from politics to reporting over a cleansing period of time.