Italy, a coup by the representatives of the PD

Following the resignation of Enrico Letta, this Thursday 13.02, and the almost "auto" proclamation of Matteo Renzi as Prime Minister in Italy, we see a fundamental question of democracy: Enrico Letta was elected head of his party, as Prime Minister by the Italians in the context of democratic elections. He resigned under pressure of the representatives of his party to make room for Renzi. But Matteo Renzi was never elected neither by the militants of the Democratic Party (PD) nor by the Italian people to be their Prime Minister! More, Renzi has already announced that there will be no election before ... 2018!
So, two people, with the support of one hundred thirty-six others, because sitting in the seats of power, may decide to change overnight the head of a government without calling the over 60 millions citizens to have a say on it. Is it not what is called a coup? 

Related: http://euobserver.com/political/123145