The political volatility of the tea partiers ... raises the question of how much staying power a movement based on "anti-incumbent, anti-Washington power" can have, particularly when such sentiments are so closely intertwined with the effects of the economic downturn.

The current, near-unilateral opposition on the right to the Democrats' legislative agenda has ... given focus and direction to the tea-party agitations, making alliances easier to come by. Compare such efforts to the current state of the grassroots left: having lost Bush as their primary target, liberal activists have oscillated between conducting pressure campaigns to pass Democratic bills and joining the right-wing opposition against the Democratic agenda when they feel it has fallen far short of the reforms they desire.

Should the tea-party activists lose their own oppositional momentum -- if the economy turns around, or if the Democrats quickly lose their grip in Washington -- the absence of a more constructive platform and a stable infrastructure could mean that the insurgent network could evaporate as quickly as it came.

"I don't think you're going to see a big third party movement come out of this," says Erick Erickson, a conservative activist ... "If the big problems go away on spending and growing government, the tea-party movement may go away altogether."

Cartoonist Rob Rogers does "Rob's Rough," an early look at his work and his creative process, exclusively at PG+, a members-only web site of the Pittsburgh Post-Gazette. Our introduction to PG+ gives you all the details.