Smoking could be banned in town and city centres if Mark Drakeford succeeds in becoming the next first minister.
The Welsh Labour leadership candidate has included the plan in his manifesto for the contest.
Mr Drakeford also wants to ban smoking in outdoor areas of cafes and restaurants.
Currently smoking is banned in indoor public places. It is also banned in cars where children are present. The ban is set to be extended to the grounds of schools and hospitals next summer.