Let me help you out Wendy.  Replace the word Pittsburgh with America and replace the word Paris with France.  In other words:  “... elected to represent the citizens of (America), not (France).”  English is a second language for me (I speak American) but I believe president Trump's speechwriter was attempting something called alliteration.

numb·skull /ˈnəmˌskəl/
noun informal
A stupid or foolish person.