Another political rule of thumb is being broken this year, the rule that it is "free media" -- jargon for TV and newspaper coverage the candidates don't pay for and can't control -- that drive a presidential campaign rather than "paid media."

In statewide elections, it is traditionally paid media -- ads, especially 30- and 60-second TV spots -- that supply most of the information voters get, because the electorate doesn't tend to pay much attention to free media on candidates at that level. But in presidential elections, free media has been more important because people do pay attention to those candidates and also because there is more coverage of them to pay attention to.

This year it's different, however. The primary reason is that there is just too much clutter on the free media for most of the candidates' messages to get through. It's too hard for free media to cover the 12 or 13 serious candidates (depending on whether Gary Hart is running this week or not).

Broadcast media have an especially tough problem. Each network carries only five 22-minute weeknight evening newscasts in the period between between the Iowa caucuses and the New Hampshire primary, and only 14 between New Hampshire and Super Tuesday's raft of primaries. Other stories -- Reagan and Gorbachev, Central American contras and midwestern blizzards -- must be covered as well. That leaves maybe two minutes per candidate in those crucial days.

Enter paid media. The two most notable jumps in the polls in the past 10 days -- Richard Gephardt's rise from around 6 percent to around 19 percent in Iowa, Jack Kemp's from around 5 percent to around 15 in New Hampshire -- have clearly been driven by paid media. Both candidates are making blatant attempts to appeal to local sentiment.

Gephardt calls on "workers, farmers, seniors" to support him because of his stands on trade, farm-production controls and Social Security stands; all others, it seems, need not apply.

Kemp plays to New Hampshire, America's No. 1 tax haven, by attacking George Bush and Bob Dole for supporting tax increases, and also bashes those two for favoring (in different ways) higher oil prices -- never popular in a cold state with high heating oil costs. For good measure, he also assails them for backing changes in Social Security.

The Gephardt and Kemp ads have the potential for assembling big enough (though minority) constituencies in the two states to make these little-known candidates into serious contenders. The more difficult question is whether they can carry them farther, and whether these locally accented appeals will cause them problems when they get to different terrain.

As the experience of others has shown, getting the most out of the media you pay for can be a tricky business. Paul Simon's clear, crisp ads helped him last November; they conveyed his traditional liberalism and his pleasant, folksy personality. But now, stung by Gephardt's rise, he's attacking him in speeches for supporting the 1981 tax cut and 1986 tax reform laws. He probably won't run anti-Gephardt ads, however, because negative paid media, while it may hurt the target, doesn't necessarily, in a field this large, help the guy who's buying the time. Voters who are seeking affirmative reasons to support one of several little-known candidates aren't likely to get them from a negative ad.

Michael Dukakis, Bruce Babbitt, Pete du Pont and Pat Robertson have been having different problems. For Dukakis it's lack of focus. Before Christmas he was talking about the Massachusetts miracle, but he hasn't come up with a spot or a stump speech that transfers the economic growth argument from the state to the federal level. Now he's running a spot with black-and-white stills of the dead in Nicaragua and the candidate's voice-over saying "Stop the killing." Babbitt's ads fail to convey how his pungently original mind works. Du Pont's message is too cerebral and mechanical: if you agree with my three big issue stands, vote for me. So is Robertson's: I've been a successful businessman and broadcaster, so consider me.

There are exceptions to the reliance on paid media. Gary Hart and Jesse Jackson, with the most free media and the biggest negatives, aren't running TV ads; neither is Al Haig. Al Gore is just now cutting his spots. Bush and Dole, the only two candidates the voters know in some depth, have been conducting their arguments more through free media than paid, as well-known presidential candidates have in the past.

When the fields are winnowed down, free media will probably carry most of the message again. But in the meantime, and up through Super Tuesday, the candidates' ads are going to be a major source of voters' information about them; and even if all the ads are accurate and revealing, that should leave us all at least a little uncomfortable.

The writer is a member of the editorial page staff.