SANTIAGO, Aug 24 (Reuters) - Chile"s presidential race kicked off on Tuesday after the last candidates registered late the evening before for a contest to determine who will usher in a new constitution and confront social upheaval in the world"s top copper producer. The early front-runners in the race are upstart left-wing lawmaker Gabriel Boric, 35, who hails from Chilean Patagonia, and Sebastian Sichel, 44, a tattooed independent former minister who will attempt to hold together the ruling conservative coalition. Seven other candidates from across the political spectrum joined the fray by the Monday registration deadline, ratcheting up uncertainty and raising the possibility of a spoiler, political analyst and pollster Kenneth Bunker told Reuters. Two well-known centrists - Yasna Provoste, the sitting Senate president who has been widely praised for dealmaking in Congress, and four-time presidential candidate Marco Enriquez-Ominami, each made their campaigns official . Further to the right is Jose Antonio Kast, an ultra-right lawmaker and former presidential candidate who has been compared to Brazil"s Jair Bolsonaro. Meanwhile, the List of the People, the left-wing organization that has its roots in the protest movement and won significant representation on the body drafting Chile"s new constitution, has fielded independent indigenous leader Diego Ancalao. "I would be very careful with making any projections this time around," said Bunker, of consultancy Tresquintos. "Something unexpected could happen." The Eurasia Group risk consultancy said in a report that it foresaw a second round in which "the Left is well-placed to capitalize on the demand for change." Chile, long one of Latin America"s most stable and prosperous nations, was roiled by often-violent mass protests over inequality in 2019, forcing a referendum in which voters chose to rewrite its dictatorship constitution. The candidate elected to take over from center-right President Sebastian Pinera will preside over the likely transition from the old Magna Carta, reviled by the left for its capitalist bent, to a new document currently being drafted. The new president, Bunker said, is "going to be a very symbolic figure just by inaugurating the new constitution ... and representing a changing of eras." Boric, a former student leader from the Frente Amplio (Broad Front) center-left coalition, has promised universal social benefits, decentralization and reform of Chile"s loathed private pensions system. Right-leaning Sichel, meanwhile, has said he will make tweaks to Chile"s free-market model but maintain its general tack. The turbulent time in Chile has market watchers and industry on edge, as mining, environmental and social policies are key issues in both the presidential race and the constitutional convention.