City leaders lured Democrats with lobsters, Red Sox games, and the promise of millions in corporate contributions. But in the 15 months since Boston won its first national presidential convention, the enthusiasm so marveled at by party leaders is dissolving into a logistical and political quagmire.

The event's cramped quarters in a densely packed downtown, combined with heightened security for the first national political convention since the Sept. 11 terrorist attacks, prompted the Secret (search) Service to call for the closure of two of the city's main transportation centers during the four-day gathering July 26-29.

Republican Gov. Mitt Romney (search) started a political firestorm by suggesting the convention be moved to South Boston, from the FleetCenter. Democrats took his unsolicited advice as a partisan effort to torpedo their big party.

City police unions, engaged in an ugly contract dispute with Boston Mayor Tom Menino (search), are threatening to picket.

A key piece of land near the FleetCenter may not be available for use, as promised. And fund raising, which looked so rosy at the beginning, remains an open question, especially with Romney balking at contributing any state money.

With Massachusetts Sen. John Kerry (search) as the party's presumptive nominee, the pressure is on for a smooth event.

"You have to take it all together. That's what you get with an intense level of interest," said Peggy Wilhide, spokeswoman for the Democratic National Convention Committee (search).

Democratic organizers say glitches are a normal part of convention planning, but that they have been accentuated in Boston because of anxiety over the terrorist attacks, both on Sept. 11 and, more recently, in Spain.

Other Democrats say Massachusetts' unique brand of cutthroat politics is showing its face.

"All of this is politics. How do we embarrass Democrats, how do we embarrass John Kerry in his home state," said Michael Goldman, a Democratic political consultant. "Romney's made sure that at every turn the process of working with the commonwealth has gone slowly. He seems to be doing everything he can to screw it up."

Romney denies that his suggestion last month about a change of venue for the convention was anything but a simple recommendation based on the FleetCenter's location in the dense downtown.

It is not unusual for political parties to hold their conventions in cities or states controlled by the opposite side, and partisan differences generally are put aside for the good of the local economy. Boston stands to gain $125 million or more from the roughly 30,000 delegates, visitors and journalists expected to attend the convention.

The promise of an economic bonanza was enough to bring the two sides together in Philadelphia in 2000, when a Republican convention went to a city led by a Democratic mayor.

While some Democrats believe a sprawling new convention center in South Boston might make more sense, they say the planning is too far along to change course this close to the event.

"It's not a proposal without merit," said Rep. Michael Capuano, D-Mass. "If this were a year ago, I'd probably agree with him. But the decision's been made. What's the point of bringing it up now. What's the benefit? How does that help?"