As Muslims there is no doubt that we will all be accountable for each and every one of our deeds:
يا بُنَيَّ إِنَّها إِنْ تَكُ مِثْقالَ حَبَّةٍ مِنْ خَرْدَلٍ فَتَكُنْ في صَخْرَةٍ أَوْ فِي السَّماواتِ أَوْ فِي الْأَرْضِ يَأْتِ بِهَا اللَّهُ إِنَّ اللَّهَ لَطيفٌ خَبيرٌ
O my son! Even if it should be the weight of a mustard seed, and] even though [it should be in a rock, or in the heavens, or in the earth, Allah will produce it. Indeed Allah is all-attentive, all-aware.(31:16)
Unless there were no permission from All-Mighty Allah, we would have no right to go about doing anything. We will be entitled of possessing, using, doing certain things only if our Lord gives us the permission to do so.
Furthermore, we all know if for a fact that sending Prophets has been terminated:
ما كانَ مُحَمَّدٌ أَبا أَحَدٍ مِنْ رِجالِكُمْ وَ لكِنْ رَسُولَ اللَّهِ وَ خاتَمَ النَّبِيِّينَ وَ كانَ اللَّهُ بِكُلِّ شَيْءٍ عَليماً
Muhammad is not the father of any man among you, but he is the Apostle of Allah and the Seal of the Prophets, and Allah has knowledge of all things.(33:40)
Taking into consideration the above-mentioned facts, I'd like to raise a question:
Who has been given the permission from Allah to chose the ruler of an Islamic government? Who is entitled to appoint the leader? Could you please give me an answer based on Qranic verses or authentic traditions?
Just Sunni's point of view please.