The author asks:

It is curious that this issue should come up so strongly now. The US jobs situation is improving. The unemployment rate is 5%, and the number of people with jobs has increased by more than 600,000 this year.

It has to do with the reality that most of these jobs are low wage positions with little opportunity for advancement. Upward mobility is at an all time low. The middle class, widely considered as the consumption engine of any successful economy, is getting tightly squeezed more and more. Sure we put people to (mostly service) work, which took us off life support, but we're far from healthy as an economy. We're still straddled with massive amounts of student debt. The "under 30" crowd is having a hard time affording important life milestones like family, house, kids, etc. They're straining under the realization that they are worse off today than their parents were at their age.

Quantitatively speaking there's a great deal of evidence of this in long term interest rates. They're still extremely low, despite the Fed providing such easy money in the short term. It's a strong sign that the economy is pessimistic about the future growth of the US. And of course the lack of sufficient growth is what we're experiencing. We have become stagnant. That's no way forward.

The trade issue surfaces in this context, and it's not just trade. The issues of universal healthcare, free public universities, and more aggressive redistribution are all intertwined. And the irony of this is that it's nothing new. This is basically the New New Deal. It's a resurrection in spirit of the bargain that FDR offered the wealthy -- pay your taxes, support social programs, compensate American workers fairly, and in exchange you will protect the peaceful society within which you will all prosper.