None of the articles I've read mention religion or race. Perhaps these omissions are due to political correctness, but both of these factors are known to be drivers of party affiliation in the US. This makes it really hard to guess what the ultimate dominant issue actually was, if anything.

I do agree that the Dems should be taking more credit (and giving credit to liberal democracy in general) for improving the quality of life, which is ultimately the subject matter of economics.