As the only tea party group making significant advertising buys, Tea Party Express has become one of the most potent forces in the protest movement. The PAC raised $5.39 million through early August, all in single donations of $5,000 or less, by tapping into a database of supporters that now surpasses 400,000 people.

Much of the group’s success is because of Russo, whose political expertise gives the PAC media firepower in its efforts to elect fiscally conservative candidates…

“A lot of these tea partyers are extremely frustrated Americans who are new to politics,” [Merksamer] said. “He’s a talented political operative who has been doing this a long time.”

But that’s exactly what rankles others in the movement, who view Russo and his colleagues as professional GOP consultants exploiting the grass roots.

“These are folks who have done what so many feared would be done: They tapped into the movement to raise money for their own interests,” said Mark Meckler, co-founder and national coordinator for Tea Party Patriots, an online network of local groups.