The SPD is a middle-left party in the same way as CDU is middle-right. Most of the really left base split with the SPD after the Harz reforms in the Schröder era and founded together with the PDS(former SED) a new party named Die Linke.
If red is an indicator of a socialist party then the us repulicans are in big trouble.
If you look a the german flag and the color assosiated with the three main parties after WWII(CDU/CSU, FDP, SPD) you will see the connection.
If red is an indicator of a socialist party then the us repulicans are in big trouble.
The Republicans did not choose red, the MSM gave it to them.