While I can understand the fetish of American Liberals with the Federal level (indeed many good things in the USA are federal in nature: Civil Rights act, Roe vs Wade, New Deal, ...) I completely fail to understand what (some) European left-wingers see in the EU.

The European welfare states were created at the national level (indeed you can easily see how things like universal health-provision vary radically in their models from country to country) and most of the civilizational achievements were made independently at the national level (social security, education, ...). The "European" part of these achievements was mostly through inspiration from country to country. Other then (arguably important things) like free movement there is little to associate the EU with "prosperity".

On the other hand, I do not think it is difficult to find many examples where the EU is sinking many of the good European achievements.