Two of Atlanta’s leading business groups say lawmakers have more than a billion reasons not to pass legislation that some believe would allow for discrimination against gay Georgians.

And it’s green, as in dollars.

For the first time, the Metro Atlanta Chamber and the Atlanta Convention and Visitors Bureau, both opponents of the “religious liberty” bill now before Georgia’s Legislature, have separately produced studies that show the city and state could see a negative economic impact of $1 billion to $2 billion if Senate Bill 129 passes without civil rights protections. Those studies, obtained by The Atlanta Journal-Constitution, looked at convention and tourism business, taxes and personal wealth.

Both studies obtained by The Atlanta Journal-Constitution used the impact of similar legislation in other states to come up with estimates for Georgia and Atlanta. The studies not only show the potential losses to the state, but signal that two muscular business organizations are ready to fight the bill when lawmakers return to session in January.

Senate Bill 129, sponsored by state Sen. Josh McKoon, R-Columbus, passed the Senate this year but ran into a blockade in the House Judiciary Committee, where Republicans joined Democrats to add language making clear the bill cannot be used to legalize discrimination against anyone. Supporters said the amendment gutted the bill and they tabled it.

Passing the bill, known as the Religious Freedom Restoration Act, without the amendment would be devastating, said Katie Kirkpatrick, the chief policy officer for the Metro Atlanta Chamber.

“We want to send the message that Georgia is a welcoming state,” Kirkpatrick said. “It’s good for economic development, which is good for jobs, which is good for Georgia families. This study … allows all of us to go into the upcoming legislative session with eyes wide open as to what the potential economic risks are if Georgia doesn’t get this right.”

McKoon questioned the studies’ validity coming, as they do, from opponents of his bill.

“I suppose that if we had the money we could go hire an economist who could dream up some fantasy where RFRA would make us money,” he said. “This is just absurd.”

It’s important, McKoon said, to understand his bill is different from one that passed in Indiana. The original Indiana legislation allowed florists, bakers or other businesses to refuse service to gay couples on the basis that they oppose gay marriage for religious reasons.

Compare that, McKoon said, to “our bill, which is equivalent of the federal bill, which can only be used in a lawsuit against the government.”

It’s a false analysis, McKoon said.

But House Speaker David Ralston, R-Blue Ridge, said the studies must be considered.

“This evidence is important and relevant,” he said. “I have also had discussions with legislative leaders in Indiana and Arkansas about their experiences with this legislation. This is a serious policy debate that can have far-reaching implications for hardworking Georgians in every corner of this state and will be treated as such.”

Tom Cunningham, the chief economist for the Metro Atlanta Chamber and author of the study, found that Indiana was hit with more than 1 billion negative Twitter impressions in the week after its bill passed. “The complex dynamics of social and political reaction” of passing a bill that many fear would lead to discrimination would be felt in Georgia.

“It is unlikely that RFRA would pass and the rest of the world not care,” Cunningham wrote. “This is not what happened in the past.”

Cunningham estimates the state would lose at least $600 million in convention and business travel, and hundreds of millions more if the bill scared away the National Football League, which is expected to award Atlanta a Super Bowl after the new Falcons stadium is built.

Cunningham, who worked for the Federal Reserve for 30 years, said Georgia stockholders could also lose an average of 4 percent on investments in companies targeted for consumer boycotts.

Cunningham used the actual economic impact felt by Indiana after the Hoosier State passed similar legislation last year to estimate potential losses in Georgia. In Indiana, the public outcry was so intense, lawmakers went back just a week later and added anti-discrimination language to quiet the public storm. Still, Cunningham found, the result was intense.

“The economic fallout that Indiana experienced when the original bill first went into effect was very real and still lingers,” Kirkpatrick said. “The Indiana Legislature attempted to ‘fix’ the original bill. It was too late. The damage to the state’s image was done.”

The CVB report is based on studies done by two industry magazines, Meetings & Conventions and Successful Meetings. Those publications polled more than 100 major convention planners. The results show that about 45 percent of respondents would cancel a convention in a city where a law was passed that many of their attendees found offensive.

The CVB study estimates that Atlanta would lose 2.5 million hotel-room bookings over the next four years if a religious freedom bill passes without anti-discrimination language. That includes meetings already planned for Atlanta and estimated future bookings.

The impact would mean $450 million in lost direct spending per year, $400 million in lost business sales, $50 million in lost state and local taxes, and the loss of 4,000 jobs. All told, the CVB estimates the bill would mean a $2 billion hit to Atlanta’s tourism industry. Atlanta ranks fourth in convention business in the United States.

“You can see our concerns about passing religious freedom without any anti -discrimination language in it,” said William Pate, the president of the Atlanta CVB. “It will have a significant impact on our business. The convention business is kind of the gasoline that runs the economic engine. You don’t see it, but when it disappears you really feel it.”

Pate said lawmakers can expect to see Georgia’s business leaders at the Gold Dome in January.

“We’re going to be working with the Chamber of Commerce and several other groups as we’re down at the Capitol, urging them not to pass legislation or at the very least make sure we include nondiscriminatory language in the bill,” he said.

But McKoon said the concern is all theoretical.

“They haven’t had anyone come forward and say, ‘We’re going to cancel our convention if it passes,” he said.