Argentines will vote Sunday in the country''s first-ever presidential primary, expected to serve as a litmus test of the popularity of President Cristina Fernandez de Kirchner. Fernandez will be seeking a second four-year term on October 23 and is considered the front-runner going into Sunday''s primary. According to recent polls, though, her popularity is waning. "This primary not only serves the government so it can define its position, but it also serves the opposition, so they can do some fine-tuning to their strategies and create possible alliances," pollster Graciela Romer told the CNN.