NEW YORK (AP) _ CBS declined Monday to comment on a newspaper report that Dan Rather, the ''CBS Evening News'' anchor since he succeeded Walter Cronkite in 1981, may get Lesley Stahl or Connie Chung as a co-anchor this spring.

''There are no plans for a co-anchor'' on CBS' evening newscast, said a CBS executive who spoke on condition of anonymity.

New York Newsday quoted unidentified sources in a Saturday report that Rather, whose broadcast has been third in ratings for three successive weeks, will get a co-anchor, possibly Stahl or Chung, in hopes of boosting ratings.

CBS spokesman Tom Goodman declined to directly comment on the report.

''We're not going to engage in commenting on speculation from an unnamed source, especially with the knowledge it is not the senior management of CBS News,'' Goodman said.

Harry Reasoner and Barbara Walters were the first male and female co- anchors of an evening network newscast. But their pairing on ABC in 1976 produced low ratings and was dropped in 1978.