This blog loves to debate this question: just what the heck IS the Tea Party? Chris Good has been covering it closely and has some thoughts here, although I think he misreads Dave Weigel just a bit.: Obama and his policies are very much an animating impulse behind the movement. The best explanation I've found comes from Jonathan Rauch. He begins by noticing that conservatism is on the rise as Republican Party identification has stagnated. Independent conservatives are rising. The media calls these folks "Republican leaners."
We assume that they are LESS conservative than the average Republican and closer to the left, or the middle. But that's not true. The best evidence we have suggests that conservative independents are MORE conservative than the mean of the average Republican. These conservatives are growing their ranks. Depending upon your point of view, they're a cancerous tumor on the party, growing up and outward in all sorts of weird directions, or they're the dynamic and exuberant voices of conservative American populism.
The Tea Parties, in Rauch's comprehension, are conservatives who have left the Republican Party because of either ideology or practice AND who are currently activated, currently engaged, because they oppose the direction President Obama is taking the country. Being a member of a Tea Party is an identity. It may correlate with Republican votes, but distinctly, it is a movement that believes that the party in power has been corrupted ... corrupted by avarice, by its connections to financial interests, by the spoils of power. Right now, this force is acting like a magnet, drawing in people, refortifying their beliefs, and concentrating their fury at the size of government. (Given the choice between big business and big government, conservatives prefer the tyranny of the former; President Obama is trying to nurture a belief about the latter in a way that rejects the post-war liberal obsession with welfare. Doing so in a deep recession is very difficult.)
In the long-term, though, the electorate itself is not going to be more independent and conservative. Demography does not determine ideology, of course, but it constrains its growth in some ways and encourages its growth elsewhere. The short term trends in favor of anti-government conservative independents, trends that are correlated with aging whites, clash with stronger trends auguring population growth among minorities and single people -- the nonwhite, more secular, and younger. It may seem funny to see Tea Partiers demand that they get to keep their Medicare while decrying health benefits for others, but it is also a rational manifestation of this great melange of demographic trends.