ATLANTA — Republicans competing to become Georgia's next governor united Tuesday behind a charge to punish Delta Air Lines for cutting business ties with the National Rifle Association, while the state's term-limited GOP governor and others refrained from commenting publicly as officials worked behind the scenes to resolve the feud.Fallout from the deadly Valentine's Day school shooting in Florida engulfed Georgia politics Monday when Lt. Gov. Casey Cagle, a leading GOP gubernatorial contender, said he wants to block renewal of a major tax break for Delta after the Atlanta-based airline announced it will no longer offer discounted rates for NRA members flying to the group's conventions.Four of Cagle's Republican rivals in the 2018 race for governor said they also support halting the $38 million-per-year sales tax exemption on jet fuel that would primarily benefit Delta. One GOP candidate, Secretary of State Brian Kemp, suggested using that money instead for a "sales tax holiday" for Georgians to buy guns and ammunition tax-free.The Republican chairman of a Senate committee that approved the tax break last week said officials at the statehouse were working Tuesday to resolve the rift between GOP lawmakers and Delta.