Since the financial crisis in 2008, the richest one percent of Americans have enjoyed a recovery, buoyed by soaring stock prices and rising corporate profits. Meanwhile, the bulk of Americans have seen their wages stagnate.
The result: People are assessing their social standing in a worse light than they once did. Based on the self-assessments of Americans, the middle class has shrunk since 2008, while the lower class has dramatically grown:

[Pew]
A strong middle class has been America's engine of growth for most of the last 50 or 60 years. That's what makes the above chart so scary.
Of course, this may just be a temporary phenomenon. A real recovery with stronger wage growth would push more of those who feel as though they've fallen into the lower class back into the middle class.
But six years is a long time for a temporary phenomenon to persist and worsen. Every year that passes suggest that the trend lines above aren't just some temporary aberration. After enough time, it just becomes the norm.
So what to do? Well, a majority of Americans want government to step in to reduce poverty:

[Pew]
Further, a majority of Americans want to see higher taxes on the rich and corporations in order to spend more on assisting the poor.

Of course, the House is controlled by Republicans, and the White House and Senate are controlled by Democrats. They do not tend to agree on much, to put it mildly.
And yet... there are a few programs to help the newly expanded lower class that might be able to fly with both parties. These include increasing and extending tax breaks for businesses that hire new workers, the streamlining of costly regulations on small businesses, extra spending on improving the nation's infrastructure, and raising the minimum wage (surprisingly, yes, Republican voters do favor it).
Compromise is difficult. But when the middle class is literally falling to pieces, both sides have an urgent reason to act.