Kerry has ascended to front-runner status by tapping two strong veins — one ideological and one tactical. He has appropriated Dean's "people versus the powerful" message that appeals to liberal Democratic voters, while simultaneously portraying himself as the most able to beat President Bush in November. A new USA Today-CNN-Gallup Poll released Tuesday greatly bolstered Kerry's case; it showed him beating Bush in a mock election by 7 percentage points.

Edwards has also won votes with a populist, "two Americas" message, arguing that the gap between haves and have-nots on income, health care and other measures of well being must be narrowed. It is a message that could sell in Wisconsin, which has a long populist tradition.

Edwards and Kerry have been able to claim Dean's populist message because Dean was so defined by his opposition to the Iraq war. Once Saddam Hussein was captured in December, it defused the potency of the anti-war message among Democrats. By then, Edwards and Kerry were matching Dean on the populism while trumping him on electability and character measures.

"I think this has resonated more for Edwards than it has for Dean, and I think the reason for it is that Dean did become sort of an anti-Iraq war candidate," Fleer said. "Even though Dean tried to focus on other messages, that is what people came to identify him with. Edwards doesn't have that particular label at this point."