The movement's appeal will be tested this fall, when Tea-Party-backed candidates face broader electorates.
Former House Majority leader Dick Armey, who describes himself and his group FreedomWorks as "mentors" for the movement, calls the lack of a centralized structure a defining characteristic and an asset. "It is baffling to the left because it's a group of people who are not centrally organized," the former Texas congressman says, chortling. "There is nobody running the Tea Party movement."
Jim Sagray, 63, a retired high school science teacher from Roseville, Calif., and Tea Party supporter, agrees.
"I don't believe there are any real Tea Party leaders; I don't believe there's any real national leadership," he says. "It's largely just independent groups fed up with how things are going in our nation."
Armey calls them "the biggest swing movement on the field."
Former Republican National Committee chairman Ed Gillespie calls the Tea Party "an organic enterprise" that would reject any suggestion that it is a GOP group, though he predicts most of its backers will vote for Republican candidates in November.
Most Tea Party supporters are Republicans or Republican-leaning independents, but that doesn't mean all Republicans share their views. Their conflict, apparent in some primaries this year that pitted establishment candidates against Tea Party challengers, could signal a battle ahead for the soul of the GOP.
Among Republicans, 57% identify themselves as Tea Party supporters; 38% do not — and the two groups have distinctly different views. Non-Tea Party Republicans are twice as likely to cite the environment as an extremely or very serious danger to the country's future, for example, and much less likely to see the size and power of the federal government as a dire threat.
Another big difference between them helps explain the Tea Party's muscular influence in the party: An overwhelming 73% of Tea Party Republicans say they are more enthusiastic about voting this year than usual. Half as many, 36%, of non-Tea Party Republicans feel that way.
Tea Party supporters generally are much more engaged in this year's elections than others, fueled by a conviction that the country is at an historic turning point. In the USA TODAY Poll, 85% described themselves as extremely or very patriotic. Their events routinely feature American flags and characters in revolutionary garb.
Their faith in the Founding Fathers is a signature of the movement. Citing links to the Revolution has been a mainstay of American politics since the nation's beginnings, Lepore says, but the way the Tea Party uses those symbols and language is original. "It is a fundamentalist way of thinking of the past: The founding documents are gospel; they come alive for us," she says.
For Rick Barber, a Tea-Party-backed congressional contender in Alabama, the Founding Fathers literally come to life. One video on his campaign website shows him talking to a character dressed as Abraham Lincoln as he likens taxation to pay for bailouts and health care as "slavery." Another features him sitting at a table in a tavern, talking to characters dressed as Benjamin Franklin, Samuel Adams and George Washington.
After Barber describes the progressive income tax and health care bill as "tyrannical," an angry George Washington growls, "Gather your armies."
Many Tea Party supporters speak of the Founders in familiar terms.