Georgia voters are heading back to the polls to choose a Republican challenger for the Deep South's last white Democratic congressman.

In Tuesday's GOP runoff, state Rep. Lee Anderson of Grovetown faces construction firm CEO Rick W. Allen of Augusta for east Georgia's 12th Congressional District. The winner will face Democratic Rep. John Barrow in November.

The Republican rivals finished first and second in last month's crowded primary, but fell short of the majority needed to clinch the GOP nomination.

Anderson is running on his legislative experience and ties to fellow farmers. Allen touts himself as a political outsider with three decades of business experience.

Republicans see an opening to beat Barrow after his district was redrawn last year.

Meanwhile, north Georgia Republicans will be heading to the polls to cast their ballots in the race for the state's newest congressional seat.

State Rep. Doug Collins, a lawmaker with ties to the governor, faces conservative talk show host Martha Zoller in Tuesday's GOP runoff for the 9th Congressional District, which covers Gainesville and parts of north Georgia.

Just over 700 votes out of nearly 110,000 votes cast separated Collins from Zoller in last month's Republican primary. The winner of Tuesday's runoff will have a substantial edge in the general election given the GOP's strength in the district.

The candidates have focused heavily on proving their conservative credentials. The winner will face Democrat Jody Cooley in November.

Polls are open from 7 a.m. to 7 p.m. Tuesday.

Contributors: GPB's Joshua Stewart contributed to this report.

Tags: runoff election, Doug Collins, Martha Zoller, Rick Allen, Lee Anderson, 2012 elections, primary runoff