An AP/Roper/GfK poll (PDF) says that 31% of `likely voters' say they support the Tea Party. The same poll says that these same likely voters are 31% Democrat, 30% independent, and 30% Republican. In other words, the Tea Party is as or more popular than either of the major parties.
This poll was taken 9/13 through 9/17/2012.
The same poll says that 18% of likely voters consider themselves `liberal.' In other words, Tea Partiers outnumber liberals by 3-to-2.
When one considers the amount of bile that the news media has directed at the Tea Party, this is quite impressive.
Breitbart has more on this poll.