Taking a ride on McFun with the presidential candidate.

HIGHWAY 34, SOUTHERN IOWA—"Did you see what happened?" Howard Dean asks. He's excited, engaging in a bit of self-swooning after a campaign stop in Chariton, Iowa. The former Vermont governor is munching on a chocolate chip cookie, his legs propped on the seat across from him. "I was actually surprised at how many people came up and said they were going to support us." At a barn in Chariton, Dean spoke to about 40 people, the kind who wear trucker hats and American-flag belt buckles unironically. One supporter gave Dean a $5 check. "That is not the educated, cultural elite" that the national media say comprises the bulk of his supporters, Dean emphasizes.

It's 12:30 p.m. on Friday, and I'm riding on "McFun," the Dean van named for its personalized license plate. It's a big Ford E-350, festooned with Dean placards and bumper stickers, a loaner from a Dean supporter named McGuire who uses it to haul around his seven kids. Up to now, I've been following McFun in a van driven by a Dean campaign intern. "There are two rules on McFun," Jenn Hengstenberg, Dean's Iowa political director, tells me before I get on board. "One, you have to have fun. Two, if you have any spinal problems, let me know, because it's bumpy." McFun's low-rent allure is a pretty good reflection of the appeal of the Dean campaign.

"People have no idear"—Dean always says "idear"—"what kind of politician I am," the candidate continues. "Because they have no idear what governing Vermont is like for the most part, because they've never come up and seen it. That [crowd in Chariton] was classic Vermont. Farmers, working people, smart, maybe not so well-educated, but they read a daily newspaper every day. Literate, product of good high-school systems. Work with their hands, rural. Conservative social values, but open-minded." Later, Dean returns to the point. "It took me about three minutes to figure out what that crowd was like, and it was rural Vermont." He smiles and raises his eyebrows in a self-satisfied way.

The man clearly feels he's on a roll, and it's hard to disagree. On his two-day journey through southeastern Iowa, Dean continues to draw unexpectedly large crowds. Chariton was the third stop on a 14-hour campaign day that began with Dean bicycling a 12-mile leg of an annual cross-state bicycling tour.

Everywhere he goes, Dean offers up a Unified Field Theory of Bush Lies: If Bush will lie about the Iraq war, he will lie about anything. Leave No Child Behind is "an ill-conceived bill which turns out to be just like the Iraq war, built on misinformation." Because Houston's high-school dropout rate turned out to be inaccurate, "The whole Texas record on education was fraudulent." Bush's estate tax cut is actually "the largest inheritance tax increase in our history" because the increasing national debt will have to be paid for by our children. Bush's tax cuts aren't even really tax cuts because they've led to increases in local property taxes on the middle class. Bush is a "promise everything, do nothing" president.

This "Bush is a liar" talking point is the one Dean chooses to start my 25-minute interview with him. "I've known the president," he says. "I knew him when he was governor. And I believed him when he said he was going to be a compassionate conservative. I believed him when he said he was going to increase AmeriCorps. The only thing the president has kept his word on, as far as I can see, is he said he was going to invade Iraq. And he did, but he wasn't even able to be truthful about why."

I've heard this stuff before—one of the advantages of interviewing a politician after you've heard him give eight talks in less than two days is that you can hear the prepackaged sound bites almost before they arrive—so I try to lead him in a different direction. During our talk, Dean doesn't say anything really shocking or provocative, but he doesn't appear to be doling out canned b.s., either (even when he is). It's the approach he takes with voters, and it works.

I start to ask him about something I mentioned on Friday, the fact that Dean seems a little angrier on television than he does in person. "It depends what you're watching," he interrupts. "The South Carolina debate, I was terrible. But if you watched me on Russert, I don't seem angry at all. I just say what I think." (Later in our interview, in a reference to the Russert interview, I jokingly ask Dean who the ambassador to Rwanda is. He looks sheepish. "I should find out," he says and adds, "I know how many troops we have.") Dean rolled his eyes a lot during that debate in South Carolina, the first debate of the Democratic presidential primary season. "That was dumb," he says, then asks, "What else have you seen me on?" I mention clips on the TV news, unable to think of specific instances that we haven't talked about yet. Dean pauses. "I mean, you have to make your own judgment. I don't get to see myself on television, so I don't know. On the talk shows, I'm not strident. When I'm giving speeches, I get very passionate. Although, as you move into the general election, probably I'm going to be talking …"

He stops himself quickly, likely realizing that Democratic candidates aren't supposed to concede that they lurch left in the primaries, then run back to the center once they get the nomination. "You know, I'm probably not going to change a lot, because what we're doing is working," he continues, back on message. "And I think if you try to mold yourself to be somebody you're not, that's when you lose." Oh well.

At the speeches I've watched Dean give, he attacks the president quite a bit. (He began one speech, "We're going to have a little fun at the president's expense.") But he reserves his real fury for his own party. His face reddens and his voice raises when he delivers one of his biggest applause lines, that Democrats need to "stop apologizing for who we are." Why does this part of the speech make him so agitated?