Bernie Sanders v the Democratic establishment: what the battle is really about

[CentralMass]

41. About those sources in that article

One is a super PAC operated by National Nurses United that was responsible for the $300,000 donation. The union, which did not respond to a request for comment, had previously spent nearly $4.8 million on pro-Sanders advertisements during the 2016 election, according to the Center for Responsive Politics

From opensecrets.org
https://www.opensecrets.org/pacs/indexpend.php?cycle=2016&cmte=C00490375

"Independent Expenditures, Communication Costs and Coordinated Expenses as of December 07, 2017:
Grand Total: $4,979,225
Total For Democrats: $4,979,225
Total Against Democrats: $0
Total For Republicans: $0
Total Against Republicans: $0ixteen Thirty Fund, another D.C.-based progressive nonprofit"

The other groip, Sixteen Thirty Fund, that donated $100 000 is D.C.-based progressive nonprofit.

"The Sixteen Thirty Fund is a 501(c)(4) social welfare organization that serves as a fiscal sponsor for initiatives advocating for change."
How We Help
https://www.sixteenthirtyfund.org/how-we-help/
Their Projects
https://www.sixteenthirtyfund.org/project-directory/

About the Organization
https://www.sixteenthirtyfund.org/about-the-fund/

https://www.opensecrets.org/outsidespending/detail.php?cmte=Sixteen+Thirty+Fund&cycle=2018

So the campaign should probably adress it. However the sources don't seem to be corporations like Comcast (that spent over $30 million in lobbying dollars or Insurance companies that lobby against Medicare for all.