State of the convention; Despite polls and pols, will Carter's knack for winning come-from-behind races beat Reagan?

A top Carter associate was holding forth here the other night on the advantages of adversity -- as they related to the President. "When Jimmy gets thumped," this Carter associate said, "the first thing that happens is that everyone hops on him. The press says how inept he is. His critics say he's showing his lack of competence. And the polls drop and drop.

"And then, when things look so very, very bad for Jimmy, he shows this genius for turning things around.

"Like this brother Billy thing. Everyone's jumping on Jimmy for that. There seems no way back. But then he holds this press conference. He's cool. He makes a magnificent defense.And what happens? People say, 'Hey, that fellow on TV sure is smart. He sure stood up to all those reporters.'

"And the next thing you know, Carter is moving up in the polls again on the strength of a failure, not a success -- or, rather, on how he has been able to respond to what was clearly a failure in judgement."

Now this individual may have been carried away a little in making the President an unchallengable political comeback champ. Doubtless there are many others who could claim that title.

But his point is a good one: Jimmy Carter seems to have a great hidden talent for turning failure or impending failure into triumph.

Take his Camp David achievement. Part of the tribute for his accomplishment came because he was expected to fail. He was sinking in the polls and was widely preceived as less than competent. It was against this background of dire predictions that his summit success looked so spectacular. Actually, Carter showed a daring quality that had not been widely noted before.

Mr. Carter's moves to gain release of the US hostages in Iran clearly have failed. Yet for a long time, the American people rallied behind Carter in support of the United States in its problems with Iran and with the Soviets. Carter profited in the polls and in his primary battles against Ted Kennedy, almost as if he has been marking up signal successes.

Throughout his political career, Mr. Carter often has been the underdog, the unknown, given the title of "most likely to lose."

From 1975 to 1976, Mr. Carter came from "Jimmy Who?" to the White House. That is a long trip. But it is the kind of trip that Mr. Carter is said to enjoy taking.

"He really likes to be positioned well behind his opponent in a political race," another Carter adviser says. "That's why he was uncomfortable when he was so far ahead of Ford last time. He hates the 'favorite' position and worries whether he can hold it. And he almost didn't in 1976."

Carter felt very much at home last fall when the pundits and pollsters were telling him he might as well stay out of the primaries, that Kennedy was so far ahead that there was no way he could be beaten. And Carter is very comfortable with his underdog position in his race against GOP nominee Ronald J. Reagan. "Jimmy thinks he'll catch Reagan at the wire," a Carter associate says.

So watch out Ronald Reagan! Carter may be only a jogger. But he is dogged. And he loves to come from behind, just when you think you have him beaten.