LCBO staff have voted 93% in favour of a walkout should they fail to secure a new contract.
The results were announced late Tuesday night after two days of voting by the 7,500 members of OP-SEU.
Denise Davis, the head of the union bargaining team, says the outcome means the union can now return to bargaining with a strong mandate.
The key issue for the union is the government's move to sell beer, wine and cider in grocery stores -- a move the union has called "creeping privatization."
The last contract covering LCBO staff expired in March.
(With files from the Canadian Press)