Congestion relief for Interstate drivers through Cobb and Cherokee counties is one step closer.

A massive project to add optional toll lanes alongside I-75 and I-575 in those counties is set to jump a critical hurdle, according to the office of Gov. Nathan Deal. According to a spokesman for Deal and people familiar with the project, federal officials have said the project can access a crucial federally subsidized loan that could shave up to $100 million off the project cost.

The loan, which saves the project money because it is made on favorable terms, is a key to getting the $1 billion project completed. The project was set to go out to bid in June, but Deal and the state Department of Transportation decided to wait until news of the loan came through.

Having beaten out stiff competition, the project is now eligible to officially apply for the loan, said Deal spokesman Brian Robinson. Last year, only four of 39 would-be applicants were invited to apply, according to Nancy Singer, a Federal Highway Administration spokeswoman. Singer confirmed that this year Georgia has been invited to apply and noted that funding is not guaranteed.

One person with knowledge of the project said the loan would not be the full $375 million the state had sought, but would cover a substantial portion of that.

Even with the loan, Deal has said, the project isn't necessarily a done deal.

"The governor has scheduled a meeting with transportation agencies next week to discuss our next steps," Robinson wrote in an email Friday.

In an interview two weeks ago, Deal said that winning the Transportation Infrastructure Finance and Innovation Act (TIFIA) loan “would certainly make it a lot easier to go forward. But we would still have to make the final judgment call looking at what the TIFIA loan amount was, coupled with the private investment, coupled with the state’s obligations. We’re not saying that that’s a make-it-or-break-it proposition.”

Although the project would likely be built by private companies who would be repaid by toll revenue, private investment and the federal loan would still not be enough to pay for it all. Even with the full loan, the state DOT said Georgia taxpayers may have to contribute up to $350 million to the project.

Deal and Atlanta Mayor Kasim Reed together lobbied U.S. Transportation Secretary Ray LaHood for the TIFIA loan.

“We stressed to him the importance of that as a part of the funding formula that we were looking at and how important we considered it to be,” Deal said.

Transportation officials here have said that cooperation between Deal, who served with LaHood in Congress, and Reed, who has a high profile nationally, has been noticed and productive in Washington.