On the first day of December, Gena Bell walked into the lobby of the CasaMagna resort in Cancun, Mexico, both thrilled and a little wary about what was to come.

"I can't believe we're here!" she said, taking in the view of the water.

She'd had that feeling a lot recently. Two years ago, Bell was a floral arranger in Cincinnati with plenty of time on her hands (she used to trim five Christmas trees in her suburban house) and strong opinions about the direction in which the United States was going (down).

Now, she was a full-time political activist, the head of a fast-growing Ohio tea party group and an influential voice in the movement. Influential enough that Americans for Prosperity, one of the most well-heeled tea party backers in the country, had invited her to help protest a U.N. climate change conference in Cancun.

It bothered her that no one had told her why she had been invited, or just what she would be doing. But she hadn't pushed too hard to find out before saying yes. It was tough to turn down a trip to Mexico in December.

Bell changed into sandals and a summer top and got to work greeting fellow tea partiers arriving from Texas, California, all over the United States. Some she had met at tea party gatherings. Others she knew only as names in her perpetually overflowing e-mail inbox.

Nearly all of them, like Bell, had stumbled into the party after Barack Obama was elected president. They had found a calling in the early days of a chaotic, leaderless movement that beckoned to political novices who identified themselves as conservatives but felt little attachment to organized politics. With astonishing speed, the tea party evolved into a powerful force that helped overturn the political order in Washington.

But as a new cast of lawmakers takes the reins in the Capitol, Bell and many of her fellow tea partiers nationwide are feeling adrift, wondering what they are supposed to do next. The movement is changing, in their view, and not necessarily for the better.

The tea party's success has drawn hundreds of politicians and groups seeking to fasten themselves to the movement, steer it and speak for it. Millions of dollars have flowed in from corporations and rich donors, all of whom have their own ideas about what the tea party should be. This struggle for the soul of the movement has left many of its original activists facing agonizing decisions: Do they, should they, still belong?

They worry that the tea party risks selling out and losing its independence. They fear that its ragtag, rebel spirit will be drained by Washington's political pros and their establishment ways of doing business.

Bell took a more expansive view. She had welcomed the attention and resources from outside groups. Now, even she was starting to have doubts. As she mulled her future, she considered stepping away altogether and doing the unthinkable: taking a job inside government.

Bell had been delighted when Americans for Prosperity invited her to Mexico. A free-market advocacy group founded by oil billionaire David Koch, AFP was one of the nation's largest donors to GOP causes and candidates.