Mr Mandelson, who is responsible for the Dome, is visiting Epcot, the futuristic science and technology park and showcase for global design, and other exhibitions in Florida on the first part of a two-day trip to the United States next weekend.
British Embassy press officer Rob Chatterson-Dixon last night confirmed that Mr Mandelson would fly to the United States to visit Epcot and to "meet leading movers and shakers on the political scene in Washington". Mr Mandelson is due to fly from meeting Mickey Mouse in Disneyworld to Washington for the second day of the visit, when he will meet leading members of the Clinton White House and senior members of the Democratic Party in Congress.
The visit to Disneyworld follows a saga of alleged confusion, secrecy and cynicism surrounding the pounds 750m Dome project, located on the Greenwich Peninsula in south-east London. The Government has insisted it will only announce next year what exactly will go into the Dome.
At a recent meeting of the Culture, Media and Sport Select Committee, Mr Mandelson said the Dome would offer visitors "a once-in-a-lifetime experience. Nothing else will equal or follow it. It will not be a tacky theme park or a one-year white elephant".
Financial controversy has added to the Government's irritation. It paid pounds 6.3m to the small design company Imagination to come up with ideas to fill the Millennium Dome, but the company later quit the project after producing an original "blueprint" around the theme of "Time".
Rows have also been sparked by fees of up to pounds 9m, paid to the American, Mark McCormack, to bring in sponsors and the pounds 500,000, three-year salary package awarded to the project's chief executive, Jennie Page.
While movers and shakers in the United States may be queuing up to meet the Minister without Portfolio, there are many here who remain unconvinced by his Dome project.