By David Beasley
ATLANTA (Reuters) - Voters in Georgia return to the polls on Tuesday to choose a Republican candidate to challenge congressman John Barrow, the only remaining white Democrat in the House of Representatives from the Deep South, in the general election in November.
State Representative Lee Anderson and businessman Rick Allen will face each other in a runoff for their party's nomination in Georgia's 12th Congressional District after neither candidate received a majority in the July 31 primary election.
The winner of Tuesday's contest will aim to unseat Barrow, who has served in the House of Representatives since 2005 and is expected to face a tough re-election fight.
White Southern Democrats have been increasingly scarce in Congress as conservative white voters switch their allegiance to the Republican Party.
Making the November 6 election even more of a challenge for Barrow, Georgia's Republican-led legislature redrew his eastern Georgia district to increase the number of Republican voters.
The state's congressional districts were re-arranged when Georgia gained one House seat due to its rapid growth reflected in the 2010 Census.
The Republican primary for the new 9th Congressional District seat also features a runoff on Tuesday between radio talk show host Martha Zoller and Doug Collins, a state representative.
The north Georgia district is heavily Republican, and the winner of the Republican primary is expected to become the state's newest member of Congress.
Zoller would be the first female Republican to serve in Congress from Georgia if she were to win the runoff and general election, said Charles Bullock, a political science professor at the University of Georgia.
"The Republican Party in Georgia has not been as hospitable to women as the Democrats have," Bullock said. "In that sense, Zoller could be a trailblazer."
Zoller is backed by former Alaska governor and 2008 Republican vice presidential nominee Sarah Palin and former U.S. House Speaker and presidential candidate Newt Gingrich. Georgia Governor Nathan Deal and former Governor Zell Miller are supporting Collins.
The winner of the runoff will face Democrat Jody Cooley, an attorney, in the general election in November.
(Editing by Colleen Jenkins and Eric Beech)