Emily Rooney's stormy eight-month tenure as executive producer of "ABC World News Tonight" ended abruptly yesterday when she was fired and replaced by Rick Kaplan, executive producer of "PrimeTime Live."

Though "World News" has continued to top the ratings, NBC's recent successes under Executive Producer Jeff Gralnick have been making ABC nervous, and some network research is said to indicate the broadcast could be slipping into second place. Gralnick left ABC shortly after Rooney joined the network.

Phyllis McGrady, who continues as executive producer of ABC's upcoming magazine show "Turning Point," replaces Kaplan at "PrimeTime."

Rooney came to ABC with no network news experience after a stint as a news director at a Boston station and she was in hot water from the beginning. She angered the Washington bureau about two weeks into the job at a contentious meeting where she is said to have told staffers they were doing shabby work and would have to improve.

Her relationship with the bureau "never got better and only got worse," said one source.

In addition, there were reports of regular clashes with ABC anchor Peter Jennings and of a chaotic atmosphere in the newsroom in which correspondents' stories were edited and reedited by three or four different editors.

She raised a further ruckus this fall when she said in interviews with TV Guide and Electronic Media that the broadcast would take a closer look at conservative views in order to counteract the "liberal bent" of the media.

"She was impolitic and just downright stupid about how people would feel about criticism," said one source. "It's hard enough to keep friends here. She never had the trust or the support of the staff."

Kaplan, who was executive producer of "Nightline" from 1984 until he took the "PrimeTime" job in 1989, is not the most easygoing personality either, sources say, but "he's a strong leader," and the broadcast is badly in need of that.

The move reportedly solves another problem that concerned ABC executives, that of keeping "PrimeTime" co-anchor Diane Sawyer happy. Insiders say she and Kaplan did not get along and his departure is thought to be helpful during this, her contract renegotiation time.

"You heard the story that Diane Sawyer got rid of me, didn't you?" said Kaplan when reached at his office in New York. "If she was going to get rid of me, this was not the time. Her contract is up and it would be too obvious."

Kaplan admitted to "differences of opinion Diane and I have had" but said, "We had, in the last six months, put all that behind us and in fact were having a great time together."

Of Rooney he said, "It's not quite as dramatic as everybody would like to write it. Emily Rooney is a very decent, talented, smart, wonderful person. She was heroic in taking the job to start with, having no institutional memory of 'World News Tonight' or of ABC News."

Kaplan conceded, however, that "There are probably people she should have known better than she knew."

But he added, "She was not a raving bitch at all. Nor is this a case of the boys getting the girls. I have never seen executives feel worse about doing something they felt they had to do."

Rooney, who was not taking calls yesterday, apparently had a rough transition from local to network news, and longtime ABC staffers resented her.

"It just didn't work out," said ABC News spokeswoman Liz Noyer. "We have great respect for Emily and hope she will accept another position with ABC." Noyer said nothing specific had been talked about.

The moves come at time when reports are circulating that negotiations have gotten serious again with White House counselor to the president David Gergen to become ABC Washington bureau chief, a job that has been vacant since George Watson left nearly a year ago. Gergen's office denied the report yesterday.

Rooney is the second woman at ABC to be moved out of a highly visible job recently. Last week, ABC named John Cochran, formerly of NBC, its Capitol Hill correspondent, replacing Jackie Judd, who becomes a special assignment correspondent for "World News." The change leaves no woman covering any of the major Washington beats.

Said one source at the network, "In both cases they are probably better choices than were there before, but we shouldn't be in a position where you take a woman off the Hill and you don't have a woman on a major beat."

Rooney is the daughter of "60 Minutes" curmudgeon Andy Rooney.

Staff writer Tom Shales contributed to this story.