In a surprise move, Forrest Sawyer, who began as a co-anchor on the "CBS Morning News" just over two years ago, resigned from CBS News on Thursday without telling viewers of his last broadcast he was quitting. His agent, Art Kaminsky, said the anchorman's resignation was amicable and that negotiations for Sawyer to leave CBS had been going on for 10 days. Sawyer's temporary replacement will be Harold Dow, CBS said. Sawyer, 38, had co-anchored the new 90-minute version of the "Morning News" with Faith Daniels since January. He previously co-anchored its troubled, low-rated two-hour version with Maria Shriver, now at NBC. Kaminsky said Sawyer had tired of the early morning grind, and also wanted to consider inquiries from other networks, producers of syndicated programs, and PBS. Sawyer joined CBS News in 1985 from station WAGA-TV in Atlanta.