Parking attendants working for NCP in Edinburgh have voted overwhelmingly for action over pay.
It is likely that the workers will take action short of a strike will be the first move which will involve an overtime ban.
Unite (T&G) union members voted by 82.1 percent in favour of striking, while 84.1 percent voted for action short of a strike.
The parking attendants are fighting to get their wages up to the levels of their counterparts in London.
A pay offer by NCP would take the lowest-paid attendants to a basic wage of just under £12,000 a year.
The T&G is pressing for a minimum wage of nearly £14,000 this year, with a view to raising wages up to £18,000 within five years.