President Barack Obama's visage has hung over Georgia's 12th Congressional District race since the start, as national Republicans put up a billboard in Augusta during the Masters golf tournament in April tying incumbent Democratic U.S. Rep. John Barrow to the president.

Obama even has infiltrated the Republican primary — again in ways not meant to flatter — as runoff contestants Lee Anderson and Rick Allen sling accusations at each other ahead of Tuesday's vote.

An Anderson mail piece and television advertisement feature Obama in tying Allen, an Augusta construction company owner, to the 2009 federal stimulus bill. The link: A Washington political action committee Allen has supported, Associated General Contractors, backed the stimulus.

The Allen campaign has responded by trashing Anderson, a state House member from Grovetown, for his support of the T-SPLOST referendum. Though it passed in the Augusta region, the sales tax increase for transportation projects remains deeply unpopular with Republican primary voters.

"On the national level, we're seeing a president that is doing everything he can to distort a businessman's record and make it look like something it's not," said Allen's campaign manager, Scott Paradise. "And I think Lee is simply taking a page out of Barack Obama's playbook, which is not surprising considering they share the same approach on how to balance the budget — raising taxes."

One Anderson television advertisement — in perhaps the defining image of a mudslinging runoff — smears cartoon manure on Allen's face, accusing Allen of peddling falsehoods like so much fertilizer.

Anderson, who emphasizes his farming background more than his legislative service, won the most votes in the four-way July 31 primary, at 34.2 percent. Allen finished second at 25.7 percent.

Since then, the two candidates who were knocked out, Augusta attorney Wright McLeod and Dublin attorney Maria Sheffield, endorsed Anderson.

"Lee is honored by Wright McLeod and Maria Sheffield's support and their vote," Anderson campaign manager Reagan Williams wrote in an email. "Lee has been working with Wright and Maria to reach out to voters across the district."

Though Gov. Nathan Deal has not officially backed a candidate, a Deal spokesman said the governor was accurately quoted in an Anderson note to supporters in which Deal thanks Anderson for backing "my conservative tax reform agenda."

Anderson also is acting like the front-runner, refusing to debate Allen one-on-one. Williams noted that there were nearly 20 four-way debates and forums during the primary and said because of his financial disadvantage Anderson has had to spend more time meeting with voters and donors during the runoff.

Allen's campaign has drawn significantly from his personal wealth. He added $250,000 to his campaign coffers for the runoff, bringing his total self-contribution to $540,000. Anderson lent his campaign $178,000 during the primary.

Anderson is making his case through ads and mailers, including accusing Allen of "pay-to-play" politics because Allen has donated to some local Democrats and also received government contracts. Paradise, Allen's campaign manager, called the claim a "flat-out lie."

Anderson's campaign says it is hypocritical for Allen to attack Anderson for the T-SPLOST vote, because Allen's company has benefited from school projects funded by local sales taxes. Allen said he personally voted against the T-SPLOST because it would be a tax hike.

Allen's attack ads emphasize Anderson's Gold Dome ties, including taking gifts from lobbyists. Primary voters in both parties last month overwhelmingly backed a nonbinding ballot question on gift caps.

Allen's campaign insists that many of McLeod's and Sheffield's supporters are flowing its way, even if the candidates did not. Turnout likely will be lower Tuesday than on July 31, but Republicans this time will not be competing with a heated Democratic sheriff primary in Augusta that attracted crossover votes — some of whom could become Allen runoff voters.

Barrow recently started campaigning in earnest, and is sitting on a $1.39 million campaign bank account as of last month. Barrow is in his fourth term and moved from Savannah to Augusta to remain in the redrawn district, which now carries a Republican lean. National Republican groups have targeted the seat as a prime opportunity for a GOP pickup, but Barrow has consistently survived tough challenges.

Barrow is the last white Democrat in Congress from the Deep South states of Georgia, South Carolina, Alabama, Mississippi and Louisiana, and one of the few remaining fiscally conservative Blue Dog Democrats. He constantly talks about his cross-aisle appeal, but the candidate atop his ticket will remain a factor.

Even as the runoff hit a crescendo over the weekend, the National Republican Congressional Committee launched a new ad campaign against Barrow. The ad title: "Barack and John."