(CNN) -- As the Tea Party's first national convention gets under way, members are united in their anger but divided over the future of the movement.
The convention is marketed as an opportunity to bring Tea Party leaders from across the country together to network and support the movement's goals. But some see the high-ticket convention, organized by a for-profit organization, as contradictory to the group's bottom-up, grass-roots beginnings.
Tennessee Rep. Marsha Blackburn and Minnesota Rep. Michele Bachmann were supposed to speak at the convention, but both dropped out, citing problems with the for-profit status of the Tea Party Nation, the group behind the event. Former Alaska Gov. Sarah Palin is the convention's keynote speaker.
The Tea Party developed last year in protest to what its supporters saw as overspending in Washington -- by both Republicans and Democrats -- following the stimulus bill, the bank bailouts and President Obama's budget.
The anger over alleged fiscal irresponsibility in Washington was shared by a wider spectrum of voters, including independents, said John Avlon, author of "Wingnuts: How the Lunatic Fringe is Hijacking America."
Over the year, the Tea Party grew from dozens to hundreds of loosely linked groups around the country.
But as it expanded, the protests became more partisan in nature, and the Tea Party established itself as an uprising to the right of the Republican Party. While independent voters were reacting against the polarization of the two major parties, the Tea Partiers wanted Republicans and Democrats to become more polarized, Avlon said.
"What happened over the course of the summer as the town hall [meetings] got hijacked, you started to see a new kind of activist taking over the Tea Party movement," Avlon said. "As the fringe has blurred with the base, you've seen more unhinged attacks proliferate, and there still hasn't been a transition to a positive agenda."
Some Tea Party members began directing their anger at Obama, calling him a socialist and carrying posters with his face altered to resemble Hitler or The Joker.
While the more radical activists made headlines, the voices of frustrated voters -- inside and outside the Tea Party -- were being heard across the country. The White House said Republican Scott Brown's win in last month's Massachusetts Senate election was "a wake-up call." While Brown captured the support of the Tea Party, he also won over the state's independent voters.
In November, Tea Party groups received credit for affecting the outcome of a special election for New York's 23rd Congressional District. Local Republican leaders backed state Assemblywoman Dede Scozzafava because they thought she would appeal to centrists and independents. But more conservative party members revolted and instead backed Doug Hoffman, who ran on the Conservative Party line.
Scozzafava dropped out days before the race and endorsed Bill Owens, the Democratic candidate and eventual winner. The split among Republicans contributed to Owens' win.
Curtis Gans, director of the Committee for the Study of the American Electorate at American University, pointed to that election as an example of how the Tea Party's support for more conservative candidates could hurt Republicans in the upcoming elections.
"If the 'birthers' [those who say Obama wasn't born in the U.S.] and the Tea Party people win most of the primaries in the Republican Party, that may not yield as much of a Republican victory in the general election as if their more moderate elements win," he said.
As the primary season begins, Tea Partiers disagree about where the movement is heading. Rival factions are battling over who will carry the Tea Party banner. Some members worry powerful groups are "astroturfing" what they think should remain a grass-roots group.
"I don't think the Tea Party knows what's happening to the Tea Party," Sacramento party activist Jim Knapp said. "I don't think there's any question the GOP has their tentacles into the Tea Party."
Mark Meckler and Jenny Beth Martin, founders of the Tea Party Patriots, say they are proud of what the movement has accomplished, but they are frustrated that other Tea Party groups are being run by Republican political consultants forking over lots of cash for recruitment.
The Tea Party Express, a conservative bus tour that crisscrossed the country last year, was run from inside a Republican political consulting firm.
This week's convention has also been dogged by infighting, with some protesting its $549 entrance fee and its hierarchical organization.
Meckler and Martin are not going to attend. "It wasn't the kind of grass-roots organization that we are, so we declined to participate," Meckler said.
Avlon said the concerns over the proceeds have undercut the event's attempt to be a rallying point.
"They like to compare themselves to the founding fathers. Well, imagine if John Hancock was trying to make a buck off the constitutional convention," he said.
Right now, Avlon said, the Tea Party groups are trying to flex their muscle and move the Republican Party further to the right.
But the unanswered questions are where that takes the Tea Party and how it affects the GOP in the long term.
"If it helps focus the Republican Party on a core message of a return to fiscal conservatism, which it abandoned when it had unified control of Congress ... then I think that can help strengthen the party's commitment to that core unifying issue," Avlon said.
"But if it just empowers the extremes in the party, then I think when extremes control parties, when wingnuts hijack a political party -- ultimately, they take it off a cliff."
CNN's Jim Acosta contributed to this report.