Complex sentence: Ivo Sanader of HDZ (who became Croatian premier after next parliamentary elections), one of many oppositional politicians who spoke at the rally, gave a speech defending Norac and calling the government to step down.
Split into simpler sentences: Ivo Sanader of HDZ (who became Croatian premier after the next parliamentary elections) was one of many oppositional politicians who spoke at the rally. He gave a speech defending Norac and calling for the government to step down.