I wish people would stop referring to these movements as populist.  What I see is a mixture of economic and ethnic nationalism blended together to resist the global movement of people and goods in an attempt to preserve an unsustainable standard of living that was created by the post-WWII boom.  It's reactionary and relatively simplistic in terms of confronting the complex problems that have created our current situation.

Calling these people populists groups together people with a wide disparity of views and goals based simply on their opposition to the status quo.  I'm no expert but I doubt very much that economic nationalists are thrilled to be lumped together with the racist elements of the alt-right.  Dealing with the concerns of voters should start with understanding them... and distinguishing one group of views from another.