What does "demographic decline" mean?
The context: Many working-class white voters feel threatened by economic and demographic decline.

Thanks a lot!

Question

What does "demographic decline" mean?
The context: Many working-class white voters feel threatened by economic and demographic decline.

Thanks a lot!

Answer

Demographic decline = decline either in the number of people or deterioration of the structure of the population (i.e. ageing of population )

Answer

I checked from google, the meaning of demographic

adjective
1.relating to the structure of populations.

In the sentence you mentioned which might referred to the percentage of white working-class population inside the USA is decreased.