Dan Quayle is supposed to be a Robert Redford look-alike, but they gave him a Jack Kennedy haircut and sent him into the vice-presidential debate hoping to cloak him in a kind of Kennedy aura - but more conservative.

Senator Quayle himself worked hard at the comparison, leaning on Kennedy's record and youthfulness to support his own vice-presidential candidacy.It didn't work. Quayle does not have the Kennedy wit, the charm, the intellect. Sen. Lloyd Bentsen, Quayle's opponent, was probably right when he snapped: "You're no Jack Kennedy," although many must have flinched at the cold contempt with which he delivered the line.

But still, if Quayle emerged as no Kennedy, neither did he emerge as the kind of political Howdy-Doody the Dukakis-Bentsen camp has tried to represent him as.

Many Republicans are embarrassed by George Bush's choice of Quayle. There are other available Republican politicians with more experience and stature. Why not them? Why did Mr. Bush opt for Quayle?

So it was inevitable that Quayle's qualifications for the vice-presidency - and if necessary, the presidency - were central to the debate.

But the hard question that Republicans, and those leaning toward the Bush ticket, have to answer is this: Is Dan Quayle so abysmal a vice-presidential running mate that they cannot vote for George Bush?

Can those who are not wild about Quayle steel themselves to vote instead for Mike Dukakis - also no Jack Kennedy? The answer, I suspect: probably not.

Quayle fumbled and appeared ill at ease when pressed to be specific on how he would handle a sudden ascent to the presidency. Knowing the Cabinet by first name is hardly a strong recommendation for greatness. But all in all, he remained cool, in control of his material and presentation, unawed by his opponent, and unscarred by the pounding he has received from the press. He did not, as some of his critics had predicted, become breakfast for Bentsen.

He may be no intellectual heavyweight. He says he knows some world leaders. At this stage he certainly looks like a midmorning snack for a wily foe like Mikhail Gorbachev; but we should probably remember that Nikita Khrushchev chewed up Jack Kennedy at their first meeting.

But he was not a disaster in his grueling 90 minutes of character-baring. Survival, for Quayle, was victory.

Bentsen was for the most part courtly, almost statesmanlike. Indeed, it might have been a more interesting race if Bentsen and Bush were running against each other for the presidency.

But if Bentsen laid claim to more wisdom than Quayle, he had difficulty in explaining away his notion of $10,000-a-head breakfasts for lobbyists, and his major policy differences with Dukakis. Not the least among these are the divergence of opinion on capital punishment, and on aid to the Nicaraguan contras.

Bentsen keeps brushing aside these differences by saying Dukakis does not want a clone for vice-president. In tough internal debate, Bentsen says, nobody will have to ask "Where was Lloyd?" That's a cute line after Bush's problems over Iran-contra.

But a vice-president who offers too much dissent is liable to find himself not in the inner circles but in the outer corridors. Nor does it answer this question: If the voters elect Dukakis because they endorse his policies, would Bentsen overturn those policies in the event he became president?

Who won the debate? We will have to wait for analysis of the professional polls for an answer to that question. But probably this round went to the American voter.

Despite all the posturing of the candidates, despite all the programming by their handlers, despite all the attempts to influence, the country got a flash of insight into the character and thinking of the men who would be deputy king.