"Poor and Working People make up one politically homogeneous demographic." Another can be added to this: "The Democratic Party represents poor and working people."
Right-wing narratives are easy to spot, and are marketed better. All you have to do is listen to a Republican, a Tea Partier, or Fox News for five minutes, and you'll hear no less than three repetitions of some assumed and politically marketed false choice or oversimplification sold with all the truth of accepted common wisdom.
On the left, they're a little more difficult to spot. One reason is because "the left" is really a loose, bickering coalition of competing interests that can hardly agree on any issue. They usually have to cut deals to achieve policy goals, and can't often get everything they want at once because so many varied stakeholders have to be in on the deal. That's one structural reason why the right-wing is usually the group setting the terms of every political conversation.
Luckily, every once in a while, I'm reminded that a few overarching left-wing narratives do exist that tie a huge majority of "the left" together. In this case, it is a narrative often used in dismay or disgruntlement by someone on the left, who is frustrated that politics are hard, and that the Democratic, Liberal, and Progressive coalition that makes up "the left" must usually factor into their governing philosophies the political priorities of the Libertarian, Conservative, Tea Party, and Republican coalition that makes up "the right."
This is especially true when "the right" has some sort of political power or capital that they are willing to cash in to get policy concessions from "the left." Such policy concessions are not seen as a necessary part of the governing process, they are considered wholesale surrender of all progressive political priorities everywhere and for all time, that will throw us immediately back into the 3rd World poverty and vassalism of the Dark Ages.
Since the Democratic Party so obviously has broken with the Liberals and Progressives in their coalition, the only answer is a third party that really represents poor and working people.
Just like the Tea Party is waiting on a 3rd party ready to represent the wishes of Real Americans (tm).