ATLANTA - Just a few weeks ago, some suggested that Atlanta was about to choose its first white mayor in a generation. Instead, the Nov. 3 election set up a hard-fought runoff battle that is expected to break down largely along racial lines when voters return to the polls tomorrow.

City Council member Mary Norwood, who is white, and former State Sen. Kasim Reed, who is African American, are vying for a critical mass of racial crossover votes, with victory most likely hinging on black-vs.-white turnout.

"What it comes down to is if she gets more black votes than he gets white votes," said political strategist Tom Houck. "When people say race doesn't matter, obviously it does. There is no dominant issue that distinguishes these two other than she's a white woman and he's a black guy."

While the folksy Norwood, 57, contrasts with the more serious and polished Reed, 40, both have focused in their campaigns on public safety, transparency, and accountability. Norwood, who says she is an independent, has been accused of being a closeted Republican, and Reed, a Democrat, has challenged her for the votes of another key minority, gay Atlantans.

Reed has enjoyed a steady march of endorsements, keeping his name in the local media. Norwood has stuck to her grassroots strategy. Without big names touting her candidacy, she has held news conferences in blighted neighborhoods around the city.

Early voting suggests strong turnout in Norwood's stronghold. Voters on the city's northside - where most whites cast ballots - were outpacing the heavily black southside. The Thanksgiving holiday and a prediction of rain tomorrow could further depress voter turnout, which is already expected to be low. Political observers have the candidates tied.

Atlanta has had black mayors since Sam Massell, the last white mayor, was defeated in 1973. Current Mayor Shirley Franklin, a Philadelphia native, became the city's first female mayor in 2002 and is barred from seeking a third term.

Atlanta, which has about 500,000 residents, saw its black population share decline from 61 percent in 2000 to 57 percent in 2007, the latest Census figures show. Over the same period, the white population share grew from 33 percent to 38 percent.

During the general election, Norwood was widely considered the front-runner, as the crowded field of mostly black candidates fractured the city's black vote. She had considerable funding, a successful ground campaign, and notable black support, which she has cultivated in seven years on the City Council.

Reed started late with little money and hardly any name recognition. But within weeks, bolstered by high-profile endorsements, Reed saw his coffers and support grow.

Norwood took 46 percent of the vote in the six-person general election - short of the 50 percent plus one needed to avert a runoff - to Reed's 36 percent. About 33 percent of the city's 237,000 registered voters cast ballots.

"Kasim Reed was an unknown in the broader community and had nowhere to go but up," said former mayor Massell, now president of the Buckhead Coalition. Reed also stands to pick up voters from former challenger Lisa Borders, who finished a distant third in the general election. Borders, who is black, has thrown her support behind Reed.

Reed has also picked up support since the runoff from the Rev. Joseph Lowery, baseball legend Hank Aaron, and many of the city's black clergy - who could be key in mobilizing their congregations.