WHEN I was campaigning in Iowa one day last month, a guy came up to me in dead seriousness and said: "I will deliver you my caucus vote if you can provide for me quickly the Ph and sediment density of the Congo River at its mouth." It turned out this man was raising tropical fish and those from the mouth of the Congo River kept dying. I told my staff people in Iowa to look into it.

That's retail politics, American-style. And looking back on my long campaign for the Democratic nomination -- which ended last week -- I'm not sure that I would change it very much. The one thing I know I would do differently is to be born in Texas. Arizona is a mighty small base from which to walk out of the hinterlands into the cities and knock on the door and say, "I'm running for president of the United States."

There are a thousand particulars I could list to explain why I failed to do well in Iowa and New Hampshire: small political base, not well-known, complicated message, not enough money, didn't go to television charm school soon enough. But those are all superficial explanations. My basic problem was that it's too much, the first time, out to have both a new messenger and a different and challenging message.

It was kind of like the stranger riding into town on the Fourth of July and introducing himself around, a total stranger, and saying, "By the way, this party can't go on much longer. We've got to get to work rebuilding the town." It takes a lot of time to assimilate that message.

I would say to other present and potential candidates who are standing at the edge of the water hole of truth: My experience does not stand for the proposition that it's fatal to talk about taxes. That's too easy -- to say that my withdrawal from the race is conclusive proof that mentioning the "T-word" is drinking political hemlock. I don't read it that way at all. My experience stands only for a limited proposition: A newcomer riding into town with a challenging message has a hard time.

I know some things about our nominating process I wouldn't change:

The length of the campaign. Those who say it's too long are dead wrong. It has to be long, to allow us to surface national leadership outside of a parliamentary system. Congress does not automatically produce national leadership. Instead, we are stuck with a system that creates national leadership in an almost random way. That's nothing new. We have a 200-year history of national leaders emerging from the most improbable quarters. So it is important that the process be long. Two years is not a long time for a continental nation to get some inkling of what's happening.

The make-or-break early primaries. The Iowa-New Hampshire process is conceptually correct. Maybe other states should have a piece of the action. We could draw from a hat the names of several small states where the early primaries would be held. But we need a "retail" point of entry, where candidates can spend months meeting with voters in their living rooms.

The media's role. The notion that the media don't cover issues is ridiculous. I mean, every time a candidate gives off even a shred of evidence that he has something to say, it gets reported. The reason that issues don't get covered is that candidates aren't talking about them. The press does tend to run as a pack, however. There's a tendency to pile on when you're down and float you into the stratosphere when you're up. This exaggerates the normal ups and downs of a campaign. It turns a bumpy ride into a rollercoaster. But anybody who thinks the press is too powerful should look at my campaign: I got great coverage, but it did me little good with the voters.

American democracy is a wondrous process. We wait too long to confront problems. We dither in the face of challenge and emergency, sort of wandering around in complacency with our political leaders hiding in the bushes refusing to do their job. Then, when crisis strikes, we have a extraordinary capacity for rallying to action.

My guess is that this will all play out a lot faster than we expect. There will be recession out there soon -- it may even come before this election cycle is over. The recession will occur, and we will be looking about for the countercyclical Keynesian response -- which isn't going to be available. We're going to have to march through uncharted terrain -- asking how we can simultaneously match government austerity with stimulative fiscal policies -- and I don't think anybody's ever had to ask that kind of question before.

The Democrats, unfortunately, are slipping into a campaign that is based on reaction, the negative side of populism in which the enemy is "them" -- the Japanese, the Koreans, the fat cats on Wall Street. It's "their" success that's the enemy; it's "us" versus Wall Street and the foreigners. This is the old negative populism that will delay the day of reckoning.

Part of my problem as a candidate who was prepared to tell people the bad news was the Reagan legacy. They've painted reformers and truthtellers into a very tight corner. By random luck, they stumbled on the idea of a massive tax cut counterbalanced by enormous borrowing. That has had two effects. One is sustaining the standard of living for the haves; the other is opening up a budget deficit that has made it difficult to move in any direction. Anybody who proposes to diagnose what's wrong carries the burden of saying, "After seven years I'm here to tell you it can't continue." You sound like a spoilsport.

I had a problem with television, as everybody knows by now. I said after my first TV debate that if they could teach Mr. Ed to talk on TV, they could teach me. So I went to "charm school," in front of 20 million Americans, to learn things I should have learned 20 years ago. It was really wonderful. Really character-building.

So what did I learn in charm school? Very simple. There is a picture-frame protocol for television that is very different from normal public speaking. If you watch me talking to a small group, you'll see all the problems that were evident on television. I tend to move around, my gestures are too expansive. I'm out of the picture frame. When you watch me on television, you get a sense of being on a roller coaster. So I tried to learn some basic things. Look at your subject. Be conversational. Tone down your gestures. And ultimately, forget about it all and relax.

Another problem in this campaign has been that the Democrats all sounded the same, and showed little willingness to take risks. The best time was early in the campaign, when we were just giving speeches and laying out positions and talking in a less intense environment. But by the end of 1987, there was a kind of closing of the ranks. Everybody became more vague and more consensus-oriented. You saw it very strikingly with the eruption of the demonstrations on the West Bank over Christmas. The Democrats had nothing to say about it.

Our process inhibits risk-taking. Part of it is the desire for a winner among our constituency groups who have been so badly battered in the last seven years. They're so desperate to get rid of the Republicans that they don't want us to emphasize any differences, stir any debate. They say: The first one of you candidates that shows any sign of life is the one we want. The candidates also sense that Reagan really has recentered American politics in a way that makes it hard to challenge the consensus.

The heart of the campaign process this year was the debates -- and they were one of the most interesting sociological phenomena of all time. After each of them, the "big feet" of the press would be out there nudging each other and talking over the waterhole, cautiously sounding each other out to make sure their ideas weren't too nutty. Then came the spin controllers, who would move in subtly to try to shape reporters' perceptions of the debates. They even managed to train me. Rather than wading out into the audience after a debate, I learned to wade into the press.

And finally, there were us candidates, rubbing shoulders with each other before and after the debates. We were living together on the road, kind of like being in the same cabin at summer camp. It's the most unnatural thing in the world, because normally the football teams are on opposite sides of the field and opposing quarterbacks don't have a cocktail and talk to each other. But we were all assembled before each debate, surrounded by this bastion of Secret Service. And here were seven of us with nothing to do except to talk to each other. And we began to know and like each other.

It got funny sometimes. Paul Simon turned to me at the end of the NBC debate and said, "You're going to be in the first paragraph of tomorrow's stories. Good performance." Pretty soon, you're getting relaxed. I remember sitting next to Mike Dukakis, when he took an oil-import fee question and knocked it out of the park, and I said: "Mike, that was a home run. Terrific." There was even a tendency among candidates to signal each other in advance when a surprise question was coming -- for reasons of tactics and friendship.

In our case, familiarity bred friendship, instead of contempt. Maybe we got too friendly. Maybe too much time on the road together made it a less interesting show. Having so many debates was counterproductive. They had the opposite of the intended effect. Rather than being pointed debates, they had a kind of homogenizing influence.

As I think about my future, I know I don't want to become a spectator. There's a tendency for defeated candidates to think of themselves as journalists. I'm not a journalist. I am a player and I want to stay on the field, in the uniform of player, rather than writing the lofty articles about the future of American democracy. Our system is a fast-moving escalator and once they shove you off, it's kind of tough to get back on.

Iwill certainly be at the convention, I will certainly give my all to the nominee of the party. I rule out running for governor of Arizona, that's all. Even my enemies have been calling me up saying, Bruce, we'd love to have you back. I rule that out, but nothing else.

One of the toughest decisions I made at the end was not to buy television time in New Hampshire after we did badly in Iowa. We would have had to go $60,000 in debt to buy Manchester TV, $200,000 in debt to buy Boston TV. I said no. I had made a compact with my wife about this stuff as a condition of getting into this race, and I honored it to the end. And my compact was that all borrowing would be done in advance of Jan. 1, 1988.

Candidates get so deeply in debt because there's a wonderful kind of euphoria that sets into campaigns. It's the winner phenomenon. You think: We're on the five-yard line and another hundred thousand bucks will push us across!

It's so seductive. Your expectations really get distorted. After my appearance on the Marvin Kalb show, which was really my high point on television, there was an avalanche of checks -- just flooding out the mailbox every morning, based on one TV performance. And you wake up in the morning and you think, "I'll strike again like that. Any moment now I will go out and replicate that."

This piece is adapted from the transcript of a conversation Bruce Babbitt held with Washington Post editors Thursday afternoon, several hours after he withdrew from the Democratic nomination race.