The biggest stumbling block remaining between Falcons owner Arthur Blank and the $1 billion retractable-roof stadium may not be approval of a plan for the public portion of funding. It could be working out deals with two churches near the site he covets.

Mt. Vernon Baptist Church is in the middle of the favored stadium site, a chunk of land immediately south of the Georgia Dome. Friendship Baptist Church, where the late Mayor Maynard Jackson’s father once preached, is just across Martin Luther King Jr. Drive, which would have to be rerouted through the church’s property to make way for the new Falcons nest.

Both historic congregations now face the weighty decision on whether to sell out to make way for a new stadium - and if so for how much.

“There’s no exact details yet on a proposal,” Lloyd Hawk, who chairs Friendship’s board, said at a recent service. “And when we do, we will bring to the congregation a vote to decide. We are a Baptist church, and at a Baptist church all decisions go to the congregation.”

A chorus of amens echoed throughout the chapel, but afterward several worshippers said the prospect of uprooting could be divisive.

“It’s going to be hard. There’s so many parishioners who have been here for years. It’s a tradition,” said Adedamola Aluko, a 25-year-old electrical engineer. “It’s going to be a really tough sell.”

Atlanta Mayor Kasim Reed and Blank both say they prefer the site near the churches, which would keep the stadium about as close as the Dome is to MARTA and CNN Center. But they’re holding an option for a site about a half-mile north if negotiations with the churches fail.

“We’re not going to force this deal,” Reed said. “If we can’t get an agreement where both sides feel very good about the transaction, then we will move to the north site.”

Buying out the two churches could prove costly. Tax records show Friendship’s property is worth more than $1.2 million and Mt. Vernon’s tops $1.4 million. Any sale of the land could cost many times more than that.

The Georgia World Congress Center Authority, which would own a new stadium, has been negotiating to buy Mt. Vernon, while the city has led talks to purchase Friendship. Who would pay for the acquisitions is unclear, though the Falcons said in a document released Thursday that the team would contribute up to $20 million for “site acquisition and development costs” that could go toward the properties.

It’s delicate territory for Reed and his allies, who are wary of being seen as bulldozing two historic congregations at the will of business leaders. His agreement with Blank calls for the Falcons to spend about $800 million on building the new stadium, $50 million for infrastructure costs and $15 million for improvements in the surrounding neighborhood.

The public would chip in $200 million up front for construction through Atlanta’s hotel/motel taxes, and millions more from those taxes would go to financing costs as well as upgrades and operations in future years.

Both the Atlanta City Council and Georgia World Congress Center must approve the plan. If they do - city and state officials have already signaled their support - the two historic congregations will be at center stage.

Mt. Vernon, started as a storefront church in 1915, moved several times before landing at the property near the Dome, including a 1955 move because of road expansion.

Rev. Rodney K. Turner, the church’s pastor, hasn’t returned calls seeking comment. But members of the congregation had their first discussion about selling the property in January. Turner told the congregation the decision would be shared by all congregants, but he did not provide details on the talks.

Friendship’s history dates to the early days of the Civil War. When the congregation formally organized in 1866, members say it became the first black Baptist independent congregation in Atlanta. Without any property of their own, congregants initially worshipped in a train boxcar shipped in from Tennessee.

Known as the “mother church” for spawning off several spinoff congregations, Friendship’s leaders proudly recall the important role the church, a few blocks south of its current site, played in educating former slaves; Morehouse College housed classes in the congregation in 1879 and Spelman began in the church’s basement two years later.

Community activists worry that the churches’ possible relocation could be another example of black neighborhoods victimized by major development projects. One example, they note, is the impoverished minority neighborhoods cleared in the 1990s to accommodate the state-owned Georgia Dome. The dome would be destroyed when the new stadium is complete.

“Friendship has been there so many years. There’s so much history,” said Joe Beasley, a civil rights activist. “Black institutions get in the way of bulldozers and poor communities just get abused. It would be good to have the stadium in Atlanta, but the community shouldn’t lay down and play dead just because three or four people make a decision.”

The negotiations are expected to heat up as other details of the stadium agreement crystallize. Congregants said Georgia World Congress Center officials were invited to speak at Mt. Vernon on March 26. And city officials have already met several times with Friendship’s leaders to start hashing out a deal.

“I’m confident we’ll get something done,” said Reed.