But for the most part, Dr. Dean was alone as he defended his position and scolded his opponents for promising voters all kinds of programs along with a tax cut.

''What John just said is hogwash,'' said Dr. Dean.

''You cannot promise people tax cuts, college education, health care and whatever else you want, and say, 'Oh, it'll all be fine,' '' Dr. Dean said. ''That's what George Bush is doing. I want fiscal responsibility in this country, but I want to help middle-class people send their kids to college. You cannot have tax cuts and help people send their kids to college at the same time.''

The debate was unusual even in a year where there have been, by some counts, more than 30 debates, that have left the candidates numb and familiar with each other's positions. It was, according to National Public Radio, the first radio-only presidential debate since Harold Stassen and Thomas E. Dewey competed for the Republican nomination in 1948.

The candidates were seated in a room without an audience to applaud or heckle them. At one point, Representative Dennis A. Kucinich of Ohio used a prop more suited for a television venue as a way demonstrating to Dr. Dean that he could not reduce the deficit without cutting Pentagon spending, drawing an incredulous if helpful bit of narration from the host.

''Congressman Kucinich is holding up a pie chart, which is not truly effective on the radio,'' said Neal Conan, the host of ''Talk of the Nation'' and the moderator of the debate.

''Well, it's effective if Howard can see it,'' Mr. Kucinich said.

Mr. Gephardt argued that that the repeal of the tax cut was an appropriate trade-off to finance the national health care plan he has made a central part of his campaign.

''I think that we need to help everybody with health care insurance,'' he said.

Of the remaining candidates, General Wesley K. Clark has decided not to compete in Iowa after concluding he would fare poorly here, and thus skipped the debate. On Monday he issued a tax proposal that would cut taxes on the poor and middle class, while substantially raising the burden on millionaires.