This may be a bit of a blundering question, but what actions was Niemoller referring to when he wrote "they came for the socialists"? Why would the National Socialist party go after socialists?
Although Niemöller's poem has gone through a number of permutations, the Martin Niemöller Foundation's website official version refers to Sozialdemokraten, in other words, people affiliated with the Sozialdemokratische Partei Deutschlands (SPD), which was the main socialist party of Weimar Germany and one of the main opposition parties against the NSDAP. The SPD fought very hard to prevent the NSDAP from coming to power and were among the first parties banned by Hitler under the Enabling Act.
As for the NSDAP's own brand of socialism, I went into it here. The long and the short of it is that the NSDAP had a very different definition of socialism than socialist parties like the SPD.