For all Sen. Barack Obama's success raising money and generating excitement among voters, he faces a daunting challenge as he prepares to claim the nomination in August: a Democratic convention effort marred by costly setbacks and embarrassing delays.

With the Denver convention fewer than two months away, problems range from the serious -- upwardly spiraling costs on key contracts still being negotiated -- to the more mundane, like the reluctance of local caterers to participate because of stringent rules on what delegates will be eating, down to the color of the food. At last count, plans to renovate the inside of the Pepsi Center for the Democrats are $6 million over budget, which may force convention planners to scale back on their original design or increase their fundraising goals.

The convention is being organized by the Democratic National Committee, which is run by Howard Dean. Only in the past month, with the candidate claiming the nomination, has the Obama campaign been able to take over management of the convention planning. His aides are increasingly frustrated at organizers who they think spent too freely, planned too slowly, and underestimated actual costs.

The gathering in Denver on Aug. 25-29 is likely to draw intense interest as the Obama forces try to show a once-divided party rallying around the nominee.

Some of the Democratic missteps started almost immediately after planning began. The Democratic National Campaign Committee decided to rent top-quality offices in downtown Denver at $100,000 a month, only to need less than half the space, which it then filled with rental furniture at $50,000 a month. Also, the Denver host committee had told corporate donors that their contributions were not tax-deductible, rather than to encourage donations by saying the tax-exempt application was pending and expected to be approved.

And then there is the food: A 28-page contract requests food in "at least three of the following five colors: red, green, yellow, blue/purple and white." Garnishes could not be counted toward the colors. No fried foods would be allowed. Organic and locally grown foods were mandated, and each plate had to be 50 percent fruits and vegetables.

For the Democratic party, the danger is that a poorly run convention will reflect badly on the party and raise questions about Democratic management skills. And more worrisome for the Obama campaign is that it will be left with the bill for cost overruns or fundraising shortfalls.