A determined Clinton woos wary voters: blue-collar whites.Since at least the 1930s and FDR, the Democrats have been the party of blue-collar Americans. Now 2016 may be the year the party loses the white subset completely. In terms of political science, that is huge.
In recent decades largely the political home of "grievance groups," the Democrats have lost their appeal to white union members, a bloc which continues to shrink in any case. In 2016 it is likely most of these remaining will vote Trump.