IN THE LAST DAYS of campaigning before the Iowa precinct caucuses, when any little thing can make the difference, the candidates' campaign consultants are trying to supply the candidates with everything they need. In Michael Dukakis' case, they are trying to add "passion." Samplings of caucus-goer opinion have convinced them that Mr. Dukakis, touted as the manager of the "Massachusetts miracle," is seen as too cerebral and calculating. So media adviser Ken Swope listened to 10 hours of tapes of Mr. Dukakis' speeches (who says these people don't earn their money?), culled the most emotional lines and recorded them as voice-over to pictures of dead Nicaraguans and homeless Americans. Mr. Dukakis has followed up on the stump by passionately saying, "Not one dollar of contra aid. Not one. Not one!" without adding what used to be his first, rather cerebral objection -- that it violates the Rio Treaty.

If Mr. Dukakis has had a passion implant, Richard Gephardt has had an eyebrow enhancement. His problem is that his reddish-blond eyebrows, only slightly graying as he turns 47, show up hardly at all under television lights, making him look too young to be president. So his handlers, before he climbs on the hay wagon in his deep green, down-filled jacket to denounce the establishment for the video camera, apply a bit of eyebrow pencil. While Mr. Dukakis tries to echo Mr. Gephardt's Farm Belt passion, Mr. Gephardt is trying to compete with Mr. Dukakis' lush eyebrows. Welcome to the big leagues of American politics.

Of course, sometimes, as Walter Mondale's favorite Holiday Inns used to promise, the best surprise is no surprise; and in the stretch run in Iowa, Paul Simon's ads are designed to show that he is just the same aw-shucks guy he used to be. The candidate is shown in cartoons in black and white, with only his trademark bow ties in color, while his deep baritone in voice-over recounts how he got started wearing bow ties in campaigns in 1954 and has worn them ever since. "My bow tie is kind of my declaration of independence," he says, though the very fact that he talks about his bow ties so much proves his dependence on them, among the many other things it suggests about Mr. Simon's campaign.

In Bruce Babbitt's case, the symbolic drama comes not from the candidate but from the audience. "I've now got to the point," says Mr. Babbitt, "where I can get my audiences to stand up quite predictably. But it took some work," and the first time he tried it in New York, "I walked out to the edge of the stage and said to the audience, 'If you agree with me will you join me and stand up?' And nothing happened." Mr. Babbitt, like the other not very well known Democratic candidates, was looking for a gimmick for voters to remember him by, and came upon the idea of asking them to stand if they agreed with him that we need tax increases and spending cuts to get our fiscal house in order. That it's a little hokey even the candidate concedes. But unlike the talk of eyebrows, neckwear and the perception of passion, at least it's about something.