Alas I think the social democrats in South America habe begun to peak and are collapsing in on themselves. Rousseff, Bachelet and Kirchner are all mired in corruption cases and subpar approval ratings; while even the hard left leaders seem to be encountering some sticky problems.
I'm afraid that the true socialdemocrats have been always weak in Argentina and sadly the only socialdemocratic candidate running in the next election is going to perform rather poorly. As for the 'Boliviarian' leaders, there's a world of difference between Venezuela, Ecuador and Bolivia. While Maduro is in a downward spiral (partly due to past errors and partly to his self-destructive and aggressive behaviour), Correa and Morales are dealing with a better economic situation and a more calm environment (at least, that's the general impression).