Who was the religious and political leader in Islam following the death of Muhammad?

The first Rashidoon Caliph Hazrat Abu Bakar RAU was elected the highest leader of the Muslims after the death of Hazrat Muhammad SAW. He liked to be called as Khalifa -tur - Rasool. After him, Hazrat Omar RAU and the succeeding Rashidoon Caliphs were given the title: Amir-ul-Momineen.