One of the most fascinating dynamics of State of the Union addresses is the effort members of Congress make to not applaud presidential proposals of which they do not approve. The sound of no hands clapping can be thunderous.

Take, for example, the roughly 17 seconds President Clinton devoted the other night to the awful mess known as campaign finance. His observation that campaigns cost too much was drowned out by unanimous huzzahs while the last syllable still hung in mid-air. His call for passage of McCain-Feingold had Democrats, woefully behind in the soft-money race, on their feet, while most Republicans sat on their hands so hard many GOP posteriors remain dented to this day. His suggestion that TV broadcasters donate free air time in exchange for their free federal licenses was met with a bipartisan pause more pregnant than a maternity ward. The nation watched as lawmakers did quick mental calculations comparing what they’d save vs. what it would cost them in yanked contributions by cranky broadcasters. The ensuing applause was less than a smattering.

Regardless, the notion of a public-service quid pro quo has been idling around for years. With the president bringing it up and with broadcasters about to profit from not one but two free channels for the transition to digital television, now is the time to get it moving.

While the president’s words sailed right over lawmakers’ heads, they did at least catch the ear of the Federal Communications Commission. The day after the speech, the FCC announced it would launch a study on free air time for candidates. The FCC’s quick response is commendable, but it need not start this project from scratch. There are a lot of good ideas already out there.

One, for example, comes from a consortium of public-interest groups working under the auspices of the League of Women Voters. It creates a “time bank,” stocked in each election cycle with two hours of prime time from each broadcast license holder.

Candidates for federal office who meet a rather low threshold of small contributions from constituents in the home district would divide up half of the time. The other half would go to qualifying parties, major and minor, to parcel out to candidates or issues as they see fit. Participation would be voluntary — stations that did not contribute time would pay the prevailing market rate into a fund that would reimburse stations that went beyond the two-hour minimum.

The best part of the league’s plan is this: candidates who use the free time must appear on camera in person and speak in their own voices. Voters would have at least one opportunity to judge the ideas of candidates, not the cleverness of ad agencies.

The plan is modest, but even a small dent in the $500 million spent on TV in the 1996 election would be that much less influence that has to be peddled. Plus, it would give worthy but lesser-known challengers at least one shot at the public before being written off as also-rans. And that may be the real reason for the incumbents’ deafening and terrified silence.