Handel leads Deal 47 percent to 42 percent with 11 percent undecided, and the two are battling for voters who supported someone else in the July 20 primary.
The bruising campaign for the Republican nomination has attracted national attention with high-profile endorsements from such GOP stalwarts as former Alaska Gov. Sarah Palin, who is supporting Handel, and former Arkansas Gov. Mike Huckabee, who endorsed Deal.
It all ends Tuesday, when GOP voters pick a candidate to face Democratic nominee Roy Barnes and Libertarian John Monds in November.
Though Handel leads overall, the poll found Deal gets nearly a majority -- 48 percent -- of support from voters who backed a losing candidate in the primary. Those voters could be the key to Tuesday's vote, said Brad Coker, the managing director of Mason-Dixon Polling & Research, which conducted the poll.
The question is whether those voters are motivated enough to return to the polls. Coker said he would expect fewer than half of all primary voters to return Tuesday, and those who supported Handel or Deal are the most likely to vote again.
Mike Rogers, 53, of Evans, plans to vote for Handel again Tuesday, mainly because she is a woman.
"I think it's time to let a few women do things. In this state we've had everyone from Lester Maddox to Jimmy Carter. I'm just going to vote for a woman and see what she can do," he said.
But Rogers said he doesn't have anything against Deal and if Handel loses the runoff, he'll vote for Deal over Barnes because of his conservative values.
In the primary, Handel got 34 percent of the vote, followed by Deal with 23 percent. Former state Sen. Eric Johnson took 20 percent and state Insurance Commissioner John Oxendine 17 percent.
The new poll shows Handel, a former secretary of state, dominating her home base of metro Atlanta, while Deal did especially well in north Georgia, much of which he represented in Congress for 18 years. Johnson and Oxendine had their best showing in south Georgia, making voters from that region a key Tuesday.
"That belt running from Augusta to Savannah and all the way to Columbus and through Macon -- that's where the race is going to be decided," Coker said.
Poll respondents cited the economy and jobs as the top issues driving them to the polls Tuesday. Handel voters cited economic issues as the top reason they are supporting her; Deal voters cited his experience.
Russell Brown, 73, of Grovetown, said the economy was his "No. 1 issue."
"It's bad at the state level, but it's a horrendous situation at the national level," said Brown, who participated in the poll but wouldn't say whom he would vote for Tuesday, beyond "whichever one can make things work out better."
He said he doesn't want his taxes to go up but knows the debt and public services have to be paid somehow.
"This is the dilemma facing the leaders," Brown said. The founding fathers "would faint if they saw what's going on in the government now."
Handel supporter Benny Frick, of Thomson, said he wants his candidate to work to eliminate President Obama's health care overhaul.
"I've been on Medicare for many years, and it's certainly not going to help me, bringing so many more people into Medicare," he said.
Steve Visser of The Atlanta Journal-Constitution, Kevin Myrick of the Rome News-Tribune, Terry Dickson of the Georgia Times-Union, Carl Lewis of The (Macon) Telegraph and Larry Gierer of the Columbus Ledger-Enquirer contributed to this article.
Tracey McManus is a reporter for The Augusta Chronicle. Aaron Gold Sheinin is a reporter for The Atlanta Journal-Constitution.