It's a strange statement, but you don't refute it well. It's strange because "mostly-white" and "mostly-middle-to-lower-class" describe the electorate.

"During the last election, 33% of Hispanics voted for the Republican party"

What percentage of voters were Hispanic?

"Who do the rich vote for then?"

Statistically, it doesn't matter. There aren't that many of "the rich".