Speaking to Swedish Television news ahead of the debate, Karin Enström, who used to be defence minister and is now Moderate Party foreign affairs spokesman says the current Social Democratic/Green government is scared of facts when it comes to the military alliance.
The Moderates and several other parties on the centre-right want the minority government to look into what joining NATO would mean for Sweden. The government has refused.
"What is the government so scared of?", she told Swedish Television, "are they scared of getting facts about what Swedish membership of Nato would mean? I believe in getting facts and arguments do we han have an in-depth discussion and debate and then decide."
Defence policy is one area where the minority government and the centre-right parties have agreed to try to reach some kind of consensus, to stop the nationalist Sweden Democrats holding the balance of power in parliament.
Sweden, while not an official member of Nato, regularly carries out training exercises together with the alliance, and has also taken part in Nato-led missions around the world.