Populism is about the Many and the Few. With obvious growing inequality, the many get ripped off by the few in a multitude of ways not falling under the category of wage labor/surplus value. The patterns in this exploitation are the seeds of populist politics, to supplement the standard (and traditional) populist stance in defense of the working class, including labor rights and industrial action.
Even if there were no small farmers, the farm economy is replete with victims of economic oppression. In a political system stacked in favor of rural areas, we have been reminded lately, these victims have potentially disproportionate political power. The fact that they vote Republican now is irrelevant. A high percentage of union households voted for Bush -- I've heard 40%. Probably Bush's hispanic vote was in double digits too.
Re: Carrol's point about emphasizing message to the exclusion of 'ingathering' techniques, I think there is something to this. Once you get people in a hall, the way you say what you have to say is not so all-fired important. CC admits he is clueless as to how to get people there in the first place. I claim no greater wisdom, except to say that in this regard I think the form of the message does matter. Given a lower level of interest, the message has to contain something that has a mobilizing effect. Pointing out receptivity given a level of mobilization is assuming away the problem.
mbs