Georgia’s Republican former lieutenant governor was blown away by his first Democratic campaign rally after endorsing Kamala Harris. Geoff Duncan, who announced that he was backing the vice president this week despite being a lifelong Republican, told CNN that the energy at Tuesday night’s Atlanta rally was electrifying, and he urged his fellow conservatives to help defeat Donald Trump in November. “We’ve got to do better than Donald Trump,” Duncan said. As a lifelong conservative, I got to watch a fake Republican sit in the White House for four years and then almost destroy this country, and …