A Tea Party convention billed as the coming together of the grass-roots groups that began sprouting up around the country a year ago is unraveling as sponsors and participants pull out to protest its expense and express concerns about “profiteering.”

The convention’s difficulties highlight the fractiousness of the Tea Party groups, and the considerable suspicions among their members of anything that suggests the establishment.

The convention, to be held in Nashville in early February, made a splash by attracting big-name politicians. (Former Gov. Sarah Palin of Alaska is scheduled to deliver the keynote speech.) But some groups have criticized the cost  $549 per ticket and a $9.95 fee, plus hotel and airfare  as out of reach for the average tea partier. And they have balked at Ms. Palin’s speaking fee, which news reports have put at $100,000, a figure that organizers will not confirm or deny.

Tea Party events exploded last winter, as increasingly large gatherings protested the federal stimulus bill, government bailouts and proposed health care legislation. While they vary by name, specific tenets and relative embrace of anarchy, such groups tend to unite around fiscal conservatism and a belief that the federal government  whether led by Republicans or Democrats  has overstepped its constitutional powers.