Later, a source close to Mr. Gergen telephoned to say that Mr. Gergen was ''unaware of any organized intelligence operation of the kind described, but that he was aware that Mr. Halper was working on issues and the development of information for the campaign.''

The source added, ''There was definitely no reporting relationship to either Gergen or Baker during the campaign effort.'' Mr. Cline said Mr. Halper, his son-in-law, was on a ''special staff to analyze campaign issues, just as he did in the Bush campaign, and that he was responsible for looking for booby traps and studying what Carter people were saying to look for vulnerabilities.''

He added: ''I think this is all a romantic fallacy about an old C.I.A. network. I believe I have been close enough to the intelligence community for the last 40 years that I would have discovered it. Such an effort would not have been worthwhile and I believe it was not executed.'' He added, ''That does not mean that some individual or individuals didn't do something, but there was not a deliberate effort to penetrate'' the Government.

Mr. Halper's personal secretary, who now works at the White House, was reached at her home through the White House switchboard, and when asked about an information-gathering network run by Mr. Halper in the campaign, she hung up. White House operators then said she was ''unavailable.''

None of the sources said they knew of any relationship between Mr. Halper and Mr. Casey in the campaign. Tuesday, Mr. Casey denied that there was a campaign ''intelligence organization as such.''

Mr. Halper served for almost two years as deputy director of the State Department's Bureau of Politico-Military Affairs. State Department officials said the White House, and Mr. Gergen in particular, had applied a great deal of pressure to create this position for Mr. Halper.

Mr. Halper, 37 years old, also served in various capacities in the White House under Presidents Nixon and Ford. In an interview two weeks ago, Mr. Halper recalled that ''there was this material, the existence was widely known or at least generally known in the campaign.''