Rudi Arndt was a German politician of the Social Democratic Party of Germany (SPD). He served in several positions in the Hesse state government, and as the Mayor of Frankfurt between 1972 and 1977. At different points in his political career he was a member of the Landtag of Hesse and the European Parliament as well as the Frankfurt City Council.

The Progressive Alliance of Socialists and Democrats (S&D) is the political group in the European Parliament of the Party of European Socialists (PES). The Progressive Alliance of Socialists and Democrats was officially founded as a Socialist Group on 29 June 1953, which makes it the second oldest political group in the European Parliament after Renew Europe (Renew). It adopted its present-day name on 23 June 2009. Centre-left in orientation, the group mostly comprises social-democratic parties and is affiliated with the Progressive Alliance and Socialist International.