Surely it's true that in order for a party to win an election it has to persuade centrist voters, undecided voters, registered independents, etc. An average person who isn't too invested in politics.
There is no such thing as the center. There is the elite on one side, and the rest of the people on the other. You don't win election by coopting the right worldview and whine about immigrants.
I think a lot of people don't see it that way. E.g. there are many working class people across America who support Trump.
Maybe they could vote for the Democrats if the Democrats can earn more blue-collar credentials, and if they can paint the Republicans as the party of the rich. Perhaps the GOP is the party of the rich, but they now also have supporters who aren't rich at all.