What will happen constitutionally if Harper wins a minority and is not allowed to govern by the other parties? Wasn't it the threat of just such a coalition government that prompted the last election?
The prime minister may only stay in office as long as he or she retains the confidence of the House of Commons. The lower house may indicate its lack of support for the government by rejecting a motion of confidence, or by passing a motion of no confidence. Important bills that form a part of the government’s agenda are generally considered matters of confidence, as is any taxation or spending bill and the annual budget. When a government has lost the confidence of the House of Commons, the prime minister is obliged to either resign, or request the governor general to dissolve parliament, thereby precipitating a general election. The governor general may theoretically refuse to dissolve parliament, thereby forcing the prime minister to resign. The last instance of a governor general refusing to grant a dissolution was in 1926.
If this happens, I could see the other parties forming a coalition government, or another election could be scheduled. That’s the extent of my knowledge on the subject.