It is difficult to recall when last a speech, something approaching an oration, saved a failing candidacy. In recent years, speeches by public men, running for office or not, have had little influence on events. Only presidents are carefully heard, and they have given themselves over to style of forensics that reminds one of the director of a summer camp reading the regulations for properly marking the laundry.

Our politicians show us who they are, make their points and build a reputation, by remitting 12-second bursts of lanaguage on TV news broadcasts. rThey emerge as a recognizable likeness in much the same way that a sculptor makes a face -- applying hundreds of small dabs of clay to an as yet unborn bust. It is perhaps for this reason that, though we often speak of having a "national debate" on this or that topic, no one knows exactly where the debate took place or when or between whom.

So Sen. Edward Kennedy did a fine thing with his foreign policy speech last week, although they say it won't help him win the New Hampshire primary. For those of us who have not been among his admirers, it would have been nicer if the words had issued out of some other mouth, but they came from Kennedy's and constituted the long past due, fully reasoned critique of the hash President Carter has made of foreign affairs.

Jerry brown has been saying some of the same things. He was the first to ask why Carter should be reelected, so that Carter can put us in the red-alert near-war situation to rectify Carter's mistakes, but since he's been diagnosed as a lunatic by the press, Brown's views are only spasmodically recorded by the media.

Ronald Reagan, responding to criticism that he lost Iowa because he'd gotten blander than white sauce so the media couldn't pin the pathological extremist label on him, has also gone over to the attack. Like Kennedy, he too has been asking what the president is doing in his current line of work if the Afghanistan invastion hit him as such a surprise. These gibes are all directed at Carter's astonishing confession of disillusionment that Cousin Leonid turned out to be a fibber, not to say a teller of white Russian lies.

Kennedy has uttered the loudest attack on Carter from an antiwar point of view. But with Brown nowhere in sight and Kennedy generally considered a loser, the White House doesn't have to answer.

Whether or not he and Brown pick up in the polls, the senator may have generated the courage in others to defy the red, white and blue stampede and get the nebulous, national debate over the Carter conduct of foreign affairs going.

Even the belligerent spirits who wish to decorate the Indian Ocean with American naval bases and defend the oil supply lines may wonder how fair the burden of defense is. We don't buy most of the oil coming from that region, and yet our youth is to be sent along to defend the oil and maybe die for it. Why aren't German boys and French and Japanese youths being drafted and sent to fight in the Hindu Kush? As matters stand now, Americans are to sacrifice themselves so that the Japanese will have the power to run their Toyota factories and ship their cars over here to undersell us.

In his speech, Kennedy said, "Mutual assistance must be mutual. In return for strengthening their defense, the oil-producing states should assure a more certain oil supply at reasonable prices." Within hours after those words were spoken, the oil producers of the Persian Gulf announced another price rise . . . this time of $2 a barrel. American parents may harken to the Kennedy message when it hits them that their children are being sent to distant, sandy places to defend oil priced too high for them to put in the family car.

They're saying this speech is the real Kennedy, the guy that the campaign strategists and the private poll takers had kept hidden until he took his licking in Iowa. They say much the same about the now more candid, more forceful Reagan.

If so, we can coin a small adage: The one time an American politician will speak the heart's true conviction is when he's way back in the polls and has nothing to fear from honesty. If so, both these gentlemen may serve us better by losing than by winning.