This is part of an ongoing research project of mine (also related to PACE H2020 project) on party system transformations and patterns of electoral competition in Europe since 1990.
Quick takeaways
There are 3+1 major remarks to be made: (1) With the exceptions of UK and, to a smaller extent, Portugal, socialist party decline has been universal across Europe. But (2) it is worth noting that under the general rubric “socialist parties” we find a large variety of leftist parties including social democrats, former communists, left populists, militant socialists, let alone UK’s Labour Party which should be studied separately at least for the period during which a two-party system existed in that country. Finally (3) the major riddle seems to be about the decline of France’s erstwhile powerful Socialist Party (PS). As a consequence of remarks 1-3, then, (4) the comparative treatment of the entirety of cases is highly problematic and, if attempted at all, must be handled with extreme care.
