ATLANTA – Bishop Reginald Jackson stepped to the microphone at a drive-in rally outside a church in southwest Atlanta as his voice carried over a loudspeaker and the radio to people gathered in, around and on top of cars that filled the parking lot.“Let’s keep Georgia blue," Jackson said. “Let’s elect Jon Ossoff, Raphael Warnock to the United States Senate.” The presiding bishop of more than 400 African Methodist Episcopal churches in Georgia added a pastoral flourish as horns honked and supporters cheered: “If I have a witness, somebody say amen!"As Georgia becomes the nation’s political hotspot this winter before twin runoff elections Jan.