The top political consultant hired to strategize the push for a 2012 transportation sales tax referendum has left the campaign.

The loss of a key strategist is “always a thing you have to recover from,” said Kerwin Swint, political science professor at Kennesaw State University. “It doesn’t have to be fatal, but it’s something they’re going to have to work around and rebuild.”

In the referendum next year, Atlantans in a 10-county area will vote on a list of transportation projects being drawn up now by a "roundtable" of local elected officials, and on a 1 percent sales tax to fund the projects.  Advocates call approval of the plan critical to assuring that congestion does not choke the region's growth.

The referendum already faced an uphill climb to unite urban, suburban and exurban counties that have never voted as one group, and large numbers of voters with opposing views on mass transit and highways.

Disunity has grown more apparent in public recently.  At its latest meeting the chairman of the roundtable presented a plan to split up the money, which the officials rejected.  The decision they did make -- prioritizing big transit projects -- was divided, split 3-2 with representatives of distant suburbs voting against those from inner counties.

They have six days to agree on a draft of the whole list.  The final list is to be approved Oct. 15.

The consultant, Glenn Totten, said the divisions were not the reason he left.  He was among three nationally known consultants hired by a coalition of private business and civic groups for the campaign. The other two said they are on board through the referendum.

A representative of the group that hired Totten said the decision for him to leave was mutual. But Totten said that he left because the Legislature might switch the referendum date from July 2012 to November 2012, and he has too much work on his plate that fall. The date switch has been under discussion since before Totten was hired,  but he said now it seems more likely.

However, Paul Bennecke, a remaining strategist on the campaign, said Totten had not mentioned the possibility of the date change as a reason.

“It was mutually agreeable based on the time commitment necessary to see this through,” Bennecke said.

Michael Sullivan, a lawyer who represents the Gwinnett Chamber of Commerce on the private group formulating the campaign, also called the decision mutual. “Both parties decided it was probably in everybody’s best interests to part ways,” he said. He would not elaborate.

The campaign is expected to cost the private groups $5 million to $6 million.