>The KDP (German Communist Party) was strong, but never as big as the Nazi party - 350K vs. 1.2 million. The 1933 Reichstag fire was used as the excuse to finally crush them. They didn't dare try anything after that, simply because their leadership had been wiped out.
>
>(http://en.wikipedia.org/wiki/Communist_Party_of_Germany)
>(interesting theories at http://www.che-lives.com/home/modules.php?name=News&file=article&sid=111)

Good links.

Pretty much sums it up - not only were they weak financially, they also made a few wrong moves. When I said "at some point" i really meant "before NSDAP became too strong".

>update: http://www.spartacus.schoolnet.co.uk/GERkpd.htm has a table showing KDP representation in the Reichstag from 1920 to 1933. The only time they out-represented the Nazis was in 1928.

...and in the footnotes you can see that the Soviets ruling the Kominterne, and their agents in Germany, have just spread Stalin's orders, not really giving a damn what happens in Germany.