Political rivals Edward Markey and Joe Kennedy III are both planning to join striking direct care providers on the picket line.
The workers have been on strike in Lawrence since Tuesday following stalled negotiations over wage increase with Fidelity House, a human services organization supporting people with disabilities such as autism, Down syndrome, and acquired brain injury.
The 73-year-old Markey is running for a second full term in the Senate after spending decades representing Massachusetts in Congress.
The 38-year-old Kennedy — currently representing the 4th District in Massachusetts in the U.S. House — is challenging Markey in next year's Democratic Senate primary.
The contest has split Democratic activists and voters in Massachusetts.
Fellow Democratic U.S. Rep. Lori Trahan is also planning to join workers on the picket line Saturday.