When Al Gore proposed last month that he and Bill Bradley forgo television ads and go mano-a-mano in twice-weekly television debates, the television punditocracy gave a thumb's down.

But a funny thing has happened on the way to Iowa and New Hampshire. The candidates for president have debated 16 times on TV since October and will go at it twice more before the first primary on Feb. 1. In the half-century history of politics on TV, there's never been such a gabfest.

Citizens abhor political ads and appreciate debates, so this seems like a rare lurch by the political culture in a consumer-friendly direction. But there's a catch. Just two of these debates have aired on national broadcast television, neither in prime time. To have seen the others, you needed to have cable or live where the debate was held.

Mind you, the national networks have been willing to deploy their "A" list of anchors for moderator duty. Obviously, they value the debates as an opportunity for their human assets. But air time? Get serious.

And so our presidential campaign has been down-sized to a niche event on TV, suitable for cable. Meantime, the blizzard of ads has landed with gale force on broadcast stations. This month the leading station in New Hampshire, WMUR-TV, has been airing an average of 50 presidential candidate ads a day. Industry analysts estimate that across the country candidates for state and federal office will spend $600 million on TV ads in 2000--a six-fold increase over what they spent in 1972.

Follow the vicious cycle. We the public give our airwaves away to the broadcasters, who in turn sell air time to candidates. The public is repulsed by the ads and the money chase that pays for them. It drifts away from politics. Broadcasters--eyes fixed squarely on the bottom line--see politics as a ratings loser. They drift away from coverage.

The amount of time the network evening news programs have devoted to covering the 1999-2000 presidential campaign is half what it was at a comparable stage in 1996, according to the Center for Media and Public Affairs.

In California in 1998, the figures were more disturbing. The TV stations in that state's five largest cities devoted less than half of one percent of their news coverage to the governor's race during the three months preceding the election. Meantime, the gubernatorial candidates coughed up $100 million to pay their way onto those stations, 30 seconds at a pop.

There's a way out of this rut that need not involve regulation, legislation or financial burden. It merely requires that broadcasters remind themselves that they are obliged, as a condition of the tens of billions of dollars worth of licenses they receive from us for free, to serve the public interest.

A White House advisory panel charged with updating the public-interest obligations of TV broadcasters has recommended that stations voluntarily provide five minutes a night of candidate discourse in the 30 nights preceding all primary and general elections.

If they picked up on this proposal, the national networks could distill what's best about debates--unscripted exchanges on the issues--and package them into nightly segments among presidential candidates. Local broadcasters could do the same for the key state and local races in their viewing areas. And if the broadcasters chose to run these segments inside their newscasts, they wouldn't give up a penny of ad time or a second of entertainment programming.

Two mid-sized broadcast station group owners--Scripps Howard and Hearst-Argyle--have pledged to make good on this recommendation in 2000. But the major networks--CBS, ABC, NBC and Fox--have been silent. Most disappointing has been the lack of any commitment from CBS, whose president, Leslie Moonves, co-chaired the panel that made this recommendation.

The free and open exchange of ideas always has been the essence of self-government. For democracies to thrive, that exchange must take place in the largest public square. For the past 50 years, broadcast television has been our public square. As the age of the Internet dawns, it remains our public square.

We need presidential campaigns that play to an audience in the millions, not the hundreds of thousands. If the broadcasters want to send their anchors, that's lovely. What we really need is their air time.

The writer is the founder and executive director of the Alliance for Better Campaigns and a former political correspondent for The Post.