The underlying conflict between Ralph and Jack is based on Ralph's desire to work towards being rescued. He wants to build shelters, maintain a signal fire, and do everything they can to take care of the littluns and then get rescued.
Jack wants to hunt and have fun and satisfy the desires of the group for meat and for a way to combat their fear.
In chapter three, this comes to a head because Jack has been off hunting and neglecting what Ralph sees as his duties. Not only was he gone the whole time, he also hasn't been successful in the hunt. Jack has also allowed the other boys with him to neglect the rules and their duties in terms of maintaining the fire and helping to build the shelters, etc. So in this way, thanks to Jack's leadership, the choir is exacerbating the conflict by following Jack and ignoring Ralph's "rules."