A seven-day strike has been announced in the industrial dispute over the creation of an NHS subsidiary firm.
Workers set to be transferred to wholly-owned company WWL Solutions will walk out at 6am on July 17 and be on the picket line for a week.
Related: Plans for hospital firm get the green light
The longest walk-out in the bitter dispute so far was revealed on social media on Tuesday morning.
Wigan MP Lisa Nandy, a staunch supporter of the demonstrators, has already sent a message of solidarity on Twitter.
Almost 900 estates and facilities and procurement employees at the borough's hospitals are set to be transferred to WWL Solutions on August 1.
The announcement of further industrial action came on the day staff returned to work following a five-day strike.