But Ms. Armbrust said in counting on some of these cyberage systems for news delivery, the network planners "may be getting into the computer area of vaporware. They tell you how great it's going to be, but then it doesn't necessarily happen that way."

One senior CNN executive said, "Nobody knows how much money there will ever be in the on-line end of the business."

Mr. Murdoch's announcement generated more skepticism than the earlier announcements because unlike NBC or ABC, he is starting up a news channel without an existing network news division. The Fox news service consists of a small staff that provides reports for affiliates of the News Corporation's network.

NBC's channel, a partnership with the Microsoft Corporation to begin in July, will have access to 20 million homes because it will be a reformatted version of NBC's existing America's Talking channel. ABC, whose parent Capital Cities/ABC is completing a merger with the Walt Disney Company, has no distribution deals in place but will rely on ABC's position as the leading broadcast news network; it will start up early next year.

"NBC announced a channel, and it has both a news organization and a guarantee of solid distribution," said a senior news executive at a competing network, who spoke on condition of anonymity. "ABC announced a channel, and it has a news organization but no distribution. Now Murdoch announces a channel, and he has neither."

What Mr. Murdoch does have is Mr. Ailes, who experienced great success running two cable channels, CNBC and America's Talking, for NBC, which is owned by General Electric. He left earlier this month when NBC transformed America's Talking to its all-news channel -- and gave control over to Andrew Lack, the president of NBC News.

As Mr. Ailes left NBC, it was widely expected he would join forces with Mr. Murdoch, since both men share a background supporting conservative political causes. Indeed Mr. Murdoch in the past has suggested that his all-news channel would provide a conservative voice to counter what he called the liberal skew of coverage on CNN, which is owned by the Turner Broadcasting System.