The union said the Post Office was “on the path to extinction” as the ballot saw an overwhelming majority of 83.2% vote in favour of industrial action.
Dave Ward, CWU general secretary, said: “Staff in the Post Office face 2,000 job losses this year, the closure of their pension scheme and a strategy of slash and burn from the board of the company.
“The Post Office is at crisis point and the Government has to step in.”