Disdain for the Less Educated Is the Last Acceptable Prejudice This contempt for workers stems from the elite's unabiding faith in meritocracy, that the most-talented and hardest-working people will rise to the top. As Barrack Obama would often posit in his speeches, "You can make it if you try." That is if you don't make it it's your fault. This is the dominant ideology of the liberal intelligentsia and the ruling elites they serve. But as Harvard's Michael Sandel points out, meritocracy should more accurately be called dynastyocracy: Moreover: there aren't enough "good jobs" to go around - Brookings Institution How Liberals Turned on the Working Class
I think you will find that Democrats consistently support organized labor while Republicans support workers who are willing to work for low wages and accepting of hazardous work environments.
Then you haven't been paying close enough attention. It was Bill Clinton who passed NAFTA. It was Obama, Hillary and Biden who pushed TPP. Rahm Emanuel Reveals Dems Class War Against Its Own Voters: Rahm Emanuel: Suburbia is emerging as a new Democratic base 'This will be the year of the Biden Republican,' Rahm Emanuel says https://www.politico.com/story/2015/06/bernie-sanders-hillary-clinton-119082
People who do real physical hard work, especially those who do it out in the elements, the kind of work that built America, are no longer appreciated or properly rewarded financially in the good old USA. If it were not for migrant farm laborers we would all be starving to death, and yet we treat them like dirt.