 Socialist voters were divided between the "Esquerra" and the non-nationalist Socialists' Party of Catalonia (PSC), the sister party of the PSOE.After a period of rule by a left-wing coalition including both these parties and others, CiU under Artur Mas returned to power in 2010.In the 2015 elections a pro-independence alliance including CiU, "Esquerra" and other groups won the largest number of seats, although not an absolute majority.