Don't know anything about the local politics in Massachusetts, but this state senators staff have a Teamster contract.

Teamsters Local 122, Sen. Markey Campaign Announce New Contract For Workers
Campaign workers for Sen. Ed Markey's re-election campaign in Massachusetts unanimously agreed to a contract with Teamsters Local 122 on Saturday, becoming the latest group of political workers to gain representation with the union – and the first in Massachusetts to be represented by any union.

As part of the agreement covering 27 staffers – which includes regional organizing directors, field organizers, communication assistants, digital media producers and finance assistants – health care benefits, the cost of which was fully covered for employees, will now also be 100 percent covered for employee families, up from 33 percent previously. In addition, the campaign created a paid time off scheduling procedure which gives workers substantial time off each week.