Casey Cagle is launching his campaign for governor with ambitious promises: A $100 million tax cut in his first 100 days and 500,000 jobs in his first term. In his campaign headquarters in an office building off of Chamblee-Tucker Road in Atlanta, the three-term Republican lieutenant governor, Gainesville native and best-known candidate to enter the race thus far talked last week with The Times about his run and laid out his platform: jobs, regulatory reform, infrastructure and workforce development Cagle is set to officially announce his campaign to supporters today after several “surprise” musical acts in Duluth’s 708-seat Infinite Energy Center theater. After 12 years as lieutenant governor, Cagle is presenting his candidacy as a continuation of the work of fellow Hall Countian Gov.