Or maybe they want to hang the Greens specifically because they are less popular in Eastern Germany than Die Linke, so that they don't alienate the large number

Or maybe they want to hang the Greens specifically because they are less popular in Eastern Germany than Die Linke, so that they don't alienate the large number of previous Linke voters. (And on a less strategic level, the subtitle of the poster suggests that it is about hanging green posters everywhere, because green is also the Third Way's party color. That 'pun' wouldn't have worked with other parties.) I also wonder if parties like The Third Way or the far-left ones aren't partially ops to split the vote on the ends of the spectrum.