After years of planning, months of vigorous campaigning and a tug of war over billions of dollars in potential road and transit projects, the fate of Tuesday's penny sales tax referendum now rests with Georgia voters.

In what's become one of the most contentious fights in modern Atlanta history, both sides revved up last-minute efforts in the 10-county metro Atlanta region to persuade undecideds such as Donnie Beaty.

"I'm still trying to get my facts straight on it," the 28-year-old Grant Park resident said Monday. "The good things I've heard is that it'll help traffic. But it doesn't look like it's going to be anytime soon." Beaty, a regular MARTA rider, also would like to see more money devoted to MARTA "instead of pouring money into new stuff."

On Monday, both sides held competing news conferences at the Capitol, with transportation referendum supporters touting its importance for job creation while opponents knocked it as a stimulus package.

Atlanta Mayor Kasim Reed and Gov. Nathan Deal appeared together to urge passage of the 10-year tax, which is expected to fund $7.2 billion worth of road, rail and bus projects throughout metro Atlanta alone. Eleven other regions in Georgia also are voting on a 1 percent tax for projects in their areas.

Both men said before a crowd of more than 100 people that the referendum was crucial to attracting jobs to the region and to Georgia. Among the supporters who joined them was U.S. Rep. John Lewis, D-Ga.

At the event that included mascots from the Braves, the Atlanta Dream and the Falcons, Reed and Deal raised the specter of competitors such as Charlotte and Houston using Atlanta's well-publicized traffic problems to lure prospective business away.

Without the referendum, Deal said Georgia doesn't have the resources to ensure an adequate transportation network for the future. He called the 1 percent tax "a historical opportunity to move our state forward," noting it had the support of much of Atlanta's business community.

"The job creators have asked Georgians to vote 'yes,' " Deal said.

A few steps away from where supporters held their news conference inside the Capitol, opponents derided the tax as a stimulus package and took shots at the millions that referendum supporters raised to buy advertising and other election aids.

Recent election campaign filings showed the main pro-referendum group, Citizens for Transportation Mobility, had raised nearly $6.5 million as of mid-July while an opposition group — the Transportation Leadership Coalition — had raised less than $15,000.

"We're built on people and shoe leather, not money," Cherokee County resident Jack Staver, president of the Transportation Leadership Coalition, told a much smaller gathering. "We call it a 'breads and meds' tax. We know this is another government stimulus program that won't help people stuck in traffic."

While voters in 10 metro Atlanta counties will choose dozens of candidates for local races such as school board and county commission, the 157-project transportation referendum has overshadowed this primary. In addition to debates, forums, telephone town halls, and other events, the referendum has been the subject of robocalls that have flooded the market.

Robert Moore of Conyers said he has gotten a few robocalls asking about his party affiliation and how he planned to vote on the referendum. He was leaning toward voting for it but took into account several recent actions by politicians — namely Deal's recent announcement ending the Ga. 400 toll next year — that prompted him to change his mind. He plans to vote against the referendum.

"It was supposed to be a temporary fix," Moore said of the toll, which had been expected to end in 2011 but was extended by Gov. Sonny Perdue in 2010. "I don't trust [politicians]. "

Recent polls fail to definitively gauge a clear outcome.

A majority of metro Atlanta voters — 51 percent — oppose the referendum, according to a recent poll by The Atlanta Journal-Constitution. Forty-two percent favored the tax while 7 percent remain undecided; the margin of error was 4 points. Experts say undecided voters on tax measures typically vote no.

But backers of the referendum insist it's a much tighter contest: Their poll recently showed 45 percent against and 47 percent in favor, a difference erased by the poll's 3-point margin of error.

James Sullivan, a lawn care service owner who spends half his workday in traffic, said he plans to vote "yes" on Tuesday.

"Hopefully it'll help get rid of some of this traffic," the Jonesboro resident said.

The campaigning has taken on the feel of a marathon run in the home stretch, with both sides going down to the wire and claiming victory.

"It's going to be a humdinger, but we win by a squeak," said John Watson, senior adviser to the campaign to pass the tax.

But Debbie Dooley of the Tea Party Patriots, which has fought the referendum, disagrees.

"The 'no' people have the momentum," said Dooley, who has had little sleep in the last few days and is "living on Red Bull" until Tuesday's vote.

The referendum's supporters showed no sign of tiring Monday, either, with plans to pass out fliers to commuters in Cumberland Galleria, the Perimeter area and downtown Atlanta, Buckhead and Midtown, as well as at the Braves-Marlins game.

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Staff writer Ariel Hart contributed to this article.