Twenty-First Century Populism, define populism as pitting "a virtuous and homogeneous people against a set of elites and dangerous ‘others’ who are together depicted as depriving (or attempting to deprive) the sovereign people of their rights, values, prosperity, identity and voice.
The Populist Moment in America argues that populism is a “movement politics” of organizing for popular empowerment or civic agency -- the capacities of ordinary people to be architects and agents of their lives, shapers of their communities and the larger world, and collaborators with others from diverse backgrounds on common challenges <12>. This organizing for civic agency necessarily includes many elements beyond formal political parties such as cooperatives, community organizations, trade unions, and popular adult educational and cultural activity.
Leaders of populist movements have most often attempted to counter what they consider undue corporate power, as well as the prevalence of corruption in political leadership. Additionally, populists typically work to appeal to the lower income constituencies of the electorate - in their words, "putting people first" - with the eventual goals of "building a cooperative commonwealth."
http://en.wikipedia.org/wiki/Populism