Portugal's main opposition Socialist Party has chosen a new leader to fight next year's general election.

Lisbon Mayor Antonio Costa collected around two-thirds of the vote in a contest with Antonio Jose Seguro, party leader for the past three years, according to results published late Sunday.

Costa challenged Seguro for the leadership after the center-left Socialists failed to establish a clear advantage in opinion polls over the center-right government, which has cut pay and raised taxes.

Socialist supporters want Costa to focus policies on economic growth instead of cutbacks, and lower an unemployment rate of 14 percent. Costa has offered few details of his plans for reducing Portugal's massive debt burden, with public debt at 129 percent of gross domestic product.

A general election is due in October 2015.