As Denver braces next month for an onslaught of Obama staffers, delegates, movie stars, Clintons, Kennedys, protesters, news media and assorted hangers-on, three contradictory visions are shaping what will no doubt be a historic Democratic National Convention.

From the tight-fisted, politically cautious Obama campaign: Don't spend too much money. Do good works. Don't revel too ostentatiously. Don't be too West Coast crunchy/green/sustainable.

From Denver Mayor John Hickenlooper and the local Convention Host's "Greening" Committee: Make sure the balloons are biodegradable. Discourage fried foods. Encourage meals with "at least three of the following colors: red, green, yellow, blue/purple, and white."

From delegates, lobbyists, law firms, caterers, Oprah: Party on.

Despite numerous reports of overspending, disorganization, lagging fundraising and some overly earnest efforts at political correctness, Democrats and Denver officials believe that the Aug. 25-28 event will be a triumph for Sen. Barack Obama.

But right now, Denver officials seem afflicted with a kind of feverish sense of foreboding, and "a particularly virulent strain, at that," says Mike Littwin, a columnist for The Rocky Mountain News. "There's a real concern here that this convention will be a disaster."

Mainly, he says, the city is worried about protesters and their potential to disrupt Denver's major-league moment. This should be the time when Denver shows the world it is no longer a cow town, but a sophisticated, low-crime, high-tech urban metropolis in a setting of unparalleled natural beauty, with a majestic, $6 billion airport, a Michael Graves-designed public library and an art museum by legendary architect Gio Ponti.

All those images could go up in smoke if some protester starts throwing sewage at the delegates.

"Nobody knows just who the protesters are, or how many," Mr. Littwin said. "It could end up being nine guys on a street corner or 10,000 people, but no one knows for sure."

Rumors about the protesters' plans and the police department's counterinsurgency measures have been flying: Will the demonstrators shoot urine from water pistols -- or worse? Will the police use weapons that shoot slime -- "pain ray" guns -- or worse?

Both sides deny everything, but dozens of groups are expected to participate in an anti-war rally and parade on Sunday, Aug. 24 to express their unhappiness with what one group, Troops Out Now, has called "the complicity of the Democratic Party in the continuing wars waged abroad and the constant war waged against people of color, workers and the poor in this country."

The city of Denver isn't taking any chances. Sunday's parade route will end six blocks from the Pepsi Center where the first three days of the convention will be held, and during the week, protesters will be confined to fenced-off demonstration areas that protest organizers call "freedom cages,"

"Democrats say they don't want Obama's coronation to be anything but a party of the people, yet they're putting people in cages," said Glenn Spagnuolo, 34, spokesperson and co-founder of Recreate68 -- the group that says it wants to hold rallies rivaling those during the Democratic convention in Chicago 40 years ago.

Local liberal Democrats expressed exasperation at the protesters.

"Here is a convention where an African American is going to be nominated, for the first time ever in history, and it's happening here in my hometown. I'm pretty jazzed about that," said Bill Menezes, editor at Colorado Media Matters, a local liberal media watchdog group. "What exactly do these people think they're going to be protesting?"

While Denver's politicians ponder the challenges coming a month from now, the Obama campaign is walking its own fine line. After an overzealous host committee member issued guidelines for "green" food being served at convention-related parties -- no fried foods, please, and multi-colored veggies are preferable -- prompting derision and hilarity on the Internet and in the national media, Obama staffers and the Democratic National Committee hastened to distance themselves from the controversy.

"It was just silly," said Natalie Wyeth, a spokeswoman for the Democratic National Committee's convention organizing committee, noting the "green" food guidelines were only suggestions, not a mandate, and that caterers at private parties can serve whatever they want. "There will be french fries and chicken fingers available at the convention," she said.

"Some of them were kind of dopey, Denver-y things," laughed Patricia Calhoun, founder and editor of Westword, Denver's alternative newspaper. "But that wasn't the DNC's doing. They and the Obama campaign have since come in and bigfooted the people who were doing all this stuff."

Now that Mr. Obama has secured the nomination, his staff has moved quickly to take over the convention planning and project an image of seriousness and purpose. There will be a "National Service Day" Aug. 27 led by Michelle Obama, and delegates will not only be encouraged to ditch the margaritas and funny hats and participate in volunteer projects, but help reduce greenhouse gases by purchasing carbon "offsets" -- at $7.50 a delegate -- money that will in turn be used to support a new renewable energy project.

So far about 20 state delegations are fully participating in the "Green Delegate Challenge," Ms. Wyeth said, and while Pennsylvania currently isn't one of them, it plans to sign on, said the state Democratic party's spokesman Abe Amoros.

The event poses huge security and technical challenges -- especially the Obama campaign's decision to move the convention from the Pepsi Center to Invesco Field on the last night for Mr. Obama's nomination speech on the 45th anniversary of Martin Luther King's "I Have a Dream" speech.

Can Denver officials pull off this particular piece of stagecraft without encountering major traffic snarls or security snafus? Colorado is, after all, the only state that has ever turned down a chance to host the Olympics -- the winter games in 1976 -- although the reasons were less about self-confidence than money, damage to the environment and the impact on growth. Since then Denver has hosted the NBA All-Star Game, a G-8 Summit, a visit from the pope and last year's World Series.

"If this involved the Denver Broncos you wouldn't hear a peep about it," said Mr. Menezes, noting that when a freak October blizzard shut down most of Denver's highways, "the police made sure the buses carrying the Broncos to the airport got through the snowdrifts and you barely heard anyone say boo."

One of the loudest boos these days is coming from Charlie Brown, a flamboyant -- and politically unaffiliated -- member of Denver's City Council. He's rankled both convention planners and protesters, who at one point issued a news release demanding that Mr. Brown "be reprimanded for saying members of Recreate68 are 'cruising for a bruising.' "

His complaints are getting traction, though: After he and other city council members complained that DNC vehicles were being allowed to fill up at city-owned, tax-free fuel stations, Democratic party officials promised to reimburse the city.

Moreover, the notoriously frugal Obama campaign cancelled 56 separate delegation parties, instead combining them into one event at the Colorado Convention Center.

Nonetheless, people will be coming to Denver determined to have a good time, and an estimated 7,000 to 10,000 private parties will be popping up around town. Television talk show diva and early Obama supporter Oprah Winfrey is rumored to be throwing her own bash, and, closer to home, Pennsylvania's delegation has been soliciting corporate sponsors since January to underwrite a series of breakfasts, lunches and two dinners for its 181-member delegation, said Mr. Amoros.

"I'm shocked at the number of parties I haven't been invited to," joked Ms. Calhoun, noting that Westword has been having a little fun at the delegates' expense, publishing cartoons and satiric commentary of all 50 states.

"We're going to make fun of everyone, including ourselves," said Ms. Calhoun, who noted that the mind games have already begun. "A local artist 'punked' Recreate68 by distributing false flyers claiming to be by from a local cop wanting to beat up the protesters. They got all mad, but it was just performance art," she said.

"We're going to get through this. And come August 29th, when the last delegate has cleared out, Denver will still be standing."