DENVER, SEPT. 9 -- About a month after Gary Hart's abrupt withdrawal from the 1988 presidential campaign, a former Hart campaign worker received an angry call from the ex-candidate. Hart criticized his former aide for talking to reporters writing post-mortems on the campaign. "I'm disappointed in you," Hart said. The ex-staffer recalls that he wasn't sure whether to laugh or cry.

"YOU'RE disappointed in ME!" the aide said he replied in exasperation. "What do you think people like me are thinking?"

One of Hart's chief goals in his appearance on the ABC-TV "Nightline" program Tuesday was to apologize to that former aide and all the other backers across the country whose hopes were dashed when Hart's conduct brought an end to the campaign.

In an interview that was evidently painful, Hart said he does not plan to reenter the 1988 race and acknowledged that he made "a very, very bad mistake" by associating with model Donna Rice last spring while he was the front-runner for the Democratic nomination.

"I should not have been in the company of a woman not a friend of mine or my wife," Hart said.

He confessed that in the course of his marriage -- including two separations -- he has not been "absolutely faithful." He refused to answer specific questions about his relationships with Rice or any other woman. He expressed regret that he had "disappointed" his friends and his two children.

"No one's perfect and I wasn't running for sainthood," Hart said. "We have had presidents who had complicated private lives, to say the least." Hart insisted that the only role he wants now is to be a voice in the nation's public policy debate.

The former Colorado senator said on the program that he hoped the interview would let him move beyond the aura of scandal surrounding him and return to the policy arena. One test of that goal will be a speech he is to give Thursday in Philadelphia, a detailed set of proposals on U.S.-Soviet relations.

It is unclear whether he succeeded with the general public in his goals, but among friends and political backers, he seems to have scored well.

"He turned the corner," said John Emerson, deputy campaign manager of Hart's 1988 race. "He was incredibly courageous in what he was willing to say . . . and he can now go on to take part in the national debate as a noncandidate who has important things to say."

Hart's advisers were less certain he had fully closed the door on a possible campaign reentry.

"He was simply not willing to make a Sherman-like statement," said David Dreyer, Hart's policy adviser, referring to Union general William Tecumseh Sherman's famous remark that he would not run if nominated or serve if elected. "For right now, he's not a candidate. But it's not clear what could happen next March or June."

Larry Lawrence, a Hart friend and financial backer in San Diego, said he hopes Hart can be persuaded to run in 1988. He said he and other friends have urged Hart to get back into the race and appeal to people who feel he was wronged when the news media began exploring his private life.

Hart had lunch yesterday in a private dining room on the 107th floor of the World Trade Center with two other prominent noncandidates, New York Gov. Mario M. Cuomo (D) and Arkansas Gov. Bill Clinton (D). Although nearly 50 reporters, photographers and technicians staked out the lobby and some kept riding high-speed elevators to the Windows on the World restaurant, Hart and Cuomo managed to avoid the media mob.

Clinton said later Hart seemed "relieved" after his Tuesday appearance. "He seemed pretty upbeat about it," Clinton said. "He was glad it was over. He just wants to go on with his life . . . giving a series of speeches, talking about the issues." Staff reporter Howard Kurtz contributed to this report.