Nate Silver posts a spot-on take on populism vs. progressivism:

Populism is not...a cogent political philosophy unto itself. Franklin Roosevelt, ..., Sarah Palin, Ronald Reagan, Adolf Hitler, Hugo Chavez, ..., Bill Clinton, Ross Perot, Newt Gingrich, George Wallace, Boris Yeltsin, Mike Huckabee, Joseph Stalin, Ron Paul and Ralph Nader can all be accredited with adopting populist framings to some degree or another -- obviously they would not agree on very much in terms of the desired outcomes of their endeavors. Just as obviously, populism has been marshaled as a force for both tremendous good and tremendous evil at various points in history.