SANTIAGO, June 24 (Reuters) - Chile's controversial HidroAysen hydropower project is feasible if a planned public transmission line materializes, its boss said on Monday, rebutting presidential favorite Michelle Bachelet's statement a day earlier that the complex isn't viable. Bachelet, a popular center-leftist who was president of Chile, the world's top copper-exporting nation, from 2006 to 2010, is widely expected to win the November presidential election against a weakened right-wing bloc. Some see her opposition to the project as potentially spelling its death sentence. HidroAysen is currently being reviewed by a special ministerial group. Many analysts say the project, a political hot potato that has triggered massive protests, is likely to remain in limbo until after the election. "It's easy to say no to a project, the point is what is your proposal and so far I haven't seen any put forth by the candidates," Daniel Fernandez, the project's executive vice president, told foreign reporters during a briefing. The project "requires a political agreement that promotes a transmission line for all projects, and in that sense HidroAysen would be viable," he added. Opponents slam HidroAysen on the grounds it would harm pristine Patagonia's rivers and hurt tourism. HidroAysen, planned deep in spindly Chile's south, requires transmission lines to channel power to Santiago, the country's capital. HidroAysen, whose generating units alone were initially seen costing $3.2 billion, will now require around $8 billion in investment, considering the transmission line, Fernandez said. Bachelet's position will likely ruffle miners, who are counting on the joint venture between leading generator Endesa Chile and partner Colbun as a key source of future energy supply in Chile. Many in economically stratified Chile feel they have not benefited from the Andean country's copper boom. Massive power projects, in part destined to satiate energy-intensive mines, have triggered growing opposition.