The second-highest vote getter is challenging Marshall Stewart for the slot on the November ballot.
Bladen County Board of Elections Supervisor Larry Hammond said early voting for the one-ticket ballot got underway Friday. Only one early voting location, the Board of Elections office, is being used. The office is located on Cypress Street in Elizabethtown.
Voting is taking place between 8:30 a.m. and 5 p.m. Monday through Friday, and 8:30 a.m. to 1 p.m. on Saturday. The last day for early voting will be Aug. 14, this Saturday.
Only Democrats and unaffiliated voters who voted Democrat will be allowed to vote in the runoff, Hammond said.
The winner in the second primary will face Republican Bill Fletcher in November.
In the July 20 primary, Stewart gathered 1,810 votes locally to Atkinson's 1,063. J.B. Buxton gathered 982 in Bladen County. Statewide, Stewart took 135,348; Atkinson 132,041, and Buxton 117,274.
For more information on voting in the runoff or in the November election, call 862-6951.