Identity Politics?

This guy here, called "the stranger" argues that in the U.S., democrats win in the cities and republican win in the countryside. I have no opinions about the accuracy of the analysis. What I want to comment upon is the prescriptive conclusion of the author, namely:

"If Democrats and urban residents want to combat the rising tide of red that threatens to swamp and ruin this country, we need a new identity politics, an urban identity politics, one that argues for the cities, uses a rhetoric of urban values, and creates a tribal identity for liberals that's as powerful and attractive as the tribal identity Republicans have created for their constituents."

and then, especially:

"We can create a new identity politics, one that transcends class, race, sexual orientation, and religion, one that unites people living in cities with each other and with other urbanites in other cities."

So it is implicit in the reasoning of this person that a political group will win not by trying to persuade those who do not agree already with the preferred platform, but by selling the preferred platform to those who already buy into it.

I find this logic rather shaky. What do you think about it?