http://en.wikipedia.org/wiki/German_presidential_election,_1925
Suppose Hindenburg does not run and Wilhelm Marx def. Karl Jarres. Or conversely, Hindenburg runs but Ernst Thalmann drops out, and Wilhelm Marx def. Hindenburg. How does history change?
I think it depends on whether the SPD and Catholic Center are able to unite in the 1932 Presidential election 2nd round, perhaps behind Heinrich Brüning.
Nobody can know what happen then. Marx as president would stabilize the Democracy, but 1929 the economy collapse so or so and who would be the winner 1932? I don't know, because with Marx as President the far-right have one enemy and they are in the 20ies more united than in the real time. The conservatives and the nationalits don't want the Republic and they would fight against it. Maybe the rise of Hitler were not so big, but in the 30ies Germany collapse and it come an authoritarian regime.
