Former senator Gary Hart said last night he has no plans to reenter the race for the 1988 Democratic presidential nomination 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 nomination.

Hart's statements, his first public comments on the scandal that destroyed his candidacy in May, were made in a live television interview on ABC's "Nightline."

In the interview, Hart would not discuss the nature of his relationship with Rice or any other women.

However, he acknowledged that in the course of his marriage -- including two separations -- he has not been "absolutely faithful." But he said his relationships were not relevent to his qualifications to be president.

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

While Hart said he is not a candidate, he did acknowledge he wants to let the people decide his future.

If Hart, while disavowing interest in the race, was hoping last night to trigger a wave of public support for him to get back in, Democratic insiders predicted it will not work.

"The political obituary has already been written for Gary Hart," said Democrat William Hamilton, whose firm is working for another candidate. "He may eventually be able to come back, but not this year."

Joseph Trippi, Hart's former deputy political director, who has stayed in touch with Hart this summer, said, "I think he is setting himself up for 1992. He understands that the best way to do that is to campaign like crazy for whoever is the nominee. If people try to draft him, he knows he is much better off not responding."

In the weeks before Hart's television appearance, several former aides circulated predictions -- which they subsequently shot down -- that Hart wanted to get back into the Democratic contest this fall.

"I don't float trial balloons," Hart said last night. "That's not my style."

The only public role he spoke of was his plan to speak out on public issues that interest him, including a new concern of his, the privacy of public figures.

Hart chided the news media for "hiding in the bushes" and "putting listening devices on walls" in its efforts to substantiate rumors about his personal life. He did not name any news organizations, and none is known to have engaged in such surveillance tactics.

He also said that while public interest in the personal lives of public figures in inevitable, "the public interest ends where a person's private life does not affect his or her performance in office."

Hart advised the media that it should "never ask another candidate" whether he or she has committed adultery because "questions like that have a very real danger of undermining the quality of our national leadership."

"No one's perfect, and I wasn't running for sainthood," Hart said of his mistakes in judgment. "We have had presidents who had complicated private lives, to say the least."

Hart also said he wanted to put his transgression "in perspective . . . . No laws were broken. No papers were shredded. No money changed hands. No one lied to Congress, and all of those things have happened in this administration."

Throughout the interview Hart apologized to staff and former supporters, and he closed with an emotional apology to his children.

In several of his answers, Hart appeared to portray himself as a victim rather than as the agent of his downfall. For example, when asked about a picture showing him balancing Rice in his lap and both of them wearing T-shirts with the inscription "Monkey Business" -- the name of the boat they had chartered last March for an overnight cruise from Miami to Bimini -- Hart said he had been "embarrassed" because Rice "dropped into my lap."

"I was embarrassed. I chose not to drop her off, and the picture was taken . . . . I was not on my watch. I let my guard down," he added.

Hart, grim-faced for most of the interview, said of his current situation: "I have no privacy. My wife has no privacy. And other innocent people have no privacy . . . . Now I have been forced to make a declaration here that I think is unprecedented in American political history. And I regret it."

He added, "The same Bible that says we are all sinners says that one of the greatest sins is to waste talent. I've been given some talent. I can't waste those talents. I've got to figure out a way to use those talents. There's one higher office than president, and that's patriot. I'm going to make speeches and try to have an impact."

Hart's interview on "Nightline" occurred two days before he is scheduled to start a national lecture tour. He is to give a foreign policy talk in Philadelphia on Thursday. He reportedly feared that the lecture would not receive serious attention because of the questions about his personal conduct.

He also is scheduled to meet Wednesday with two other Democrats who are searching for public policy roles absent presidential campaigns: New York Gov. Mario M. Cuomo and Arkansas Gov. Bill Clinton.