Former premier Matteo Renzi quit as leader of Italy’s ruling party, triggering a re-election battle against minority dissidents that threatens the stability of the center-left government. With critics from leftist factions threatening to abandon the Democratic Party, Renzi, 42, told the national assembly of the party in a Rome hotel on Sunday that he had handed in his resignation, acknowledging he was set back by defeat in the Dec. 4 constitutional referendum. “Everything stems from the referendum,” Renzi told more than 600 party delegates. “I feel responsible for the defeat, there is a before and an after. That ... (full story)