Cracks are becoming fissures in Venezuelan President Hugo Chávez's self-declared revolution, as armed groups of leftist supporters clashed in recent weeks in a rough and poor barrio in skirmishes that left at least four dead.The gunfights are the first between Chávez supporters in public and seem to illustrate the rough scramble over the benefits from Chávez's oil-fueled government as well as bitter jealousies among leaders of Chavista groups. ''Wherever you go in this country, you'll find a [poor neighborhood] . . . where there are internal fights,'' said Alberto Garrido, a longtime Chávez watcher and author of several books on the man and his ideology.