Back in Washington, the political savants have a theory that presidential candidate Edward M. Kennedy is campaigning under a cloud -- a cloud of doubt seeded by the celebrated Roger Mudd interview and other recapitulations of Chappaquiddick that have raised that incident once again to a prominent place in the public consciousness.

But on the road, there has been little evidence to support it. Chappaquiddick may be a serious problem for Kennedy, but so far it has been an invisible one. West of the Potomac, hardly anybody asks about it

The national press, made up mostly of Washington-based reporters, seems to ask about Chappaquiddick at every opportunity. When Kennedy was interviewed last week on ABC-TV, for example, eight of the 13 questions dealt with the accident and its aftermath.

But once Kennedy leaves Washington, it's a different story.

Since he formally entered the race Nov. 7, Kennedy has made about four dozen stops in 14 states. Every place he goes, he is interviewed by local reporters. In all those sessions, there has been exactly one question about Chappaquiddick -- from a television reporter in Des Moines.

Kennedy frequently ends his campaign speeches by answering questions from the audience. People ask about his Senate record, his health care plan, his reason for challenging an incumbent Democrat, his views on Iran, his brothers. But no one has yet asked a question about Chappaquiddick.

Of the hundreds of demonstrators for various causes who have greeted Kennedy on the trail, only a tiny handful have hoisted Chappaquiddick signs.

The silence on Chappaquiddick has not been lost on the candidate.

Although Kennedy feels he cannot say anything about it, he seemed delighted when the point came up in an interview Friday. "Yeah, yeah, that's right," he said. "I mean, I can't say . . . why don't you tell them in Washington?"

It is one thing, though, to report that Chappaquiddick has not been a visible issue and another thing to explain why. Neither the candidate nor his staff nor the traveling reporters can say why a subject so thoroughly massaged by the media doesn't come up.

It may be that most people are less concerned about Chappaquiddick than the moguls of the eastern media. It may be that people don't ask because they don't expect a satisfactory answer. It may be that, except for the toughened cynics who populate the national press corps, people are too polite or too shy to talk about a tragedy in front of the man responsible.

Kennedy, at least, seems to reject this last possibility.

"You could say it's embarrassment," the candidate said. "But people ask some pretty tough questions, you know.That kid in Iowa City said my crime bill was a piece of extortion. I mean, he wasn't too embarrassed to tell me that."

Still, the candidate is extremely sensitive to public feelings about Chappaquiddick and the somewhat related question of his general attitude toward the opposite sex.

Campaign staff aides say Kennedy has gained less support then he expected from liberal women. The problem seems to be that, despite the senator's profeminist voting record, many women are unhappy with the paucity of females in top Kennedy staff jobs and with their perception of Kennedy as a man who does not take women seriously.

To deal with this, Kennedy made some additions to his staff and his rhetoric this week.

On the campaign plane was Martha Angle, a political columnist who has signed on as deputy press secretary. And what was previously a two-man team of traveling ghostwriters (Cary Parker and Robert Schrum) last week became a three-person team with the addition of Doris Kearns, the historian and biographer.

Kearns said she will work off and on in the campaign when she can spare time from her current book project -- a history of the Kennedy family.

Kennedy's campaign speeches from the outset have all dwelled on the general theme that President Carter has failed as a leader. As specific proof of the general point, Kennedy has cited Carter's action, or inaction, in the fields of energy, economy, agriculture, and law enforcement.

This week, Kennedy added a new specific. Carter, he said, has been a weak leader in the fight for women's rights. In almost all his speeches now, Kennedy says Carter has given "lip service" to women's issues, but has not worked hard enough to enforce antidiscrimination laws and win approval of the Equal Rights Amendment.

In a speech here Friday he even charged that the Declaration of Independence was badly worded. It should have said, according to Kennedy, that "all persons are created equal."