The broad-shouldered man in the audience, heeding the moderator's call for the question-and-answer session to begin, leaped to his feet to say how he thought Sen. Gary Hart's luncheon speech was "intelligent . . . elegant, smooth, seamless."

"Governor," deadpanned Hart (D-Colo.), "would you please repeat that into the microphone?"

New York Gov. Mario M. Cuomo couldn't get to a microphone just then, but afterward, standing in front of the television cameras and microphones, he tossed in, "brilliant . . . excellent . . . a huge success."

Hart, no piker in the matter of paeans after nearly 12 years of training in the Senate, had by then already weighed in with his admiration of Cuomo's ability to "stir America's conscience," his "sophisticated understanding that passion is not the enemy of thought" and his "commitment to powerful ideas."

One could hardly believe that in 1984 Cuomo had gone all out to defeat Hart on behalf of former vice president Walter F. Mondale during the bitterly fought New York primary or that, in 1988, Cuomo and Hart may be fighting each other for the Democratic presidential nomination.

Today's "national issues forum," one of four that Cuomo and the New York State Democratic Party have conducted, was a love feast, as well as a titillation. Cuomo has been using the forums as a means of keeping himself in the national scene during a year in which he is tied up at home running for a second term.

Moderator Theodore Sorensen captured the spirit of the proceedings today when he remarked to an overflow audience of 600 "what a pleasure it is to be here in the presence of the next president of the United States." The punch line was a pregnant pause.

Sorensen also set a tone of Reagan-bashing -- introducing Hart as a man "who has written more books in the past few years than the president has ever read" -- that the senator was only too happy to amplify .

"You may say that America is standing tall . . . but if you preside over the decline and collapse of the steel industry in the 1980s, you cannot take pride in being a great, historic American leader," Hart said. "The chicken is coming home to roost on Ronald Reagan's doorstep some day. He may be back on his ranch, but I believe that history is just."

Hart listed several problems, including the doubling of the national debt, refusal to raise revenues and trim defense spending, and the loss of trade competitiveness, that he said will "haunt" the legacy of the Reagan administration.

Hart proposed that, instead of embarking on a Strategic Defense Initiative, the nation should pursue a Strategic Investment Initiative that would include many of the industrial policies he had espoused in his 1984 presidential bid.

He called for federally guaranteed loans to basic industries that agree to invest in plant modernization and retrain workers, and for clearing houses to steer pension funds to new ventures, investment in roads and bridges, upgrading school curriculums and expanding student loans.

Hart acknowledged that these initiatives would "require additional revenues" but said he opposes tax increases for middle- and lower-income Americans. He said the only new tax that he supports is an oil import fee.

Hart and Cuomo professed to be shocked that some saw today's event as a preview of 1988, and Cuomo needled reporters who failed to ask "substantive" policy questions and were interested only in the dross of politics.

"It is much too early," Hart said, "to be thinking about 1988."

But it was earlier still -- last Jan. 4 -- when Hart announced that he would not seek reelection to the Senate, presumably to free himself for another presidential bid.