en.wikipedia.org
Atlanta–Sandy Springs–Roswell metropolitan statistical area = 6,307,261
en.wikipedia.org
Charlotte–Concord–Gastonia, NC–SC
Metropolitan Statistical Area = 2,595,027
Both figures are for their core Metropolitan Statistical Areas only, not their greater combined statistical areas.
Puts things into a better perspective.
In any event, comparing city to city is a fool's errand. The core city of Atlanta is jammed into the relatively geographically small Fulton County and a small portion in DeKalb County. The core city of Charlotte sits in the geographically larger Mecklenburg County.
When talking of Atlanta, you have to consider Fulton, Gwinnett, DeKalb, Cobb, Douglas, Clayton, Henry, Newton and Rockdale counties which encompass the urban population.
When talking of Charlotte, you pretty much can consider Mecklenburg County alone for the urban core and principle suburbs. While the out suburbs and exurbs extend into neighboring counties, they don't offset the Republican lean of those counties.
Charlotte takes one county Democratic, while Atlanta takes nine counties Democratic.
Atlanta can take the State of Georgia blue, if its population is motivated enough.
Charlotte could take the State of North Carolina blue, but only if the Raleigh/Durham and other blue centers in the State are equally motivated.
Bottom line, Charlotte is not as close to influential as Atlanta.