State lawmakers are creating a mega-dollar plan to fix Georgia’s withering transportation system, but they’re laboring without clear and public direction from the man at the top.

Gov. Nathan Deal has sent mixed signals on transportation since the campaign trail last fall, when he spoke little about how to bridge a $74 billion transportation funding gap over the next 20 years.

He has since made clear that he supports raising at least $1 billion in additional revenue for infrastructure each year, and he has endorsed the switch from a mix of sales and excise taxes on gasoline to a straight 29.2 cents-per-gallon excise tax.

It wasn’t until last week, during the final days of the session, that he warned lawmakers he could call a special session if they fail to pass the legislation. As adjournment approaches, however, Deal has left it to legislators to work out the details, and they so far have not agreed on the main points of the bill.

The behind-the-scenes strategy is a trademark of Deal's leadership style. Now in his fifth year as governor, he has used his influence to temper controversial proposals and broker back-room compromises. But that approach bewilders some who question why Deal, who never has to face the voters again, isn't playing a more vocal role.

“It’s surprising that after so much was made of the fact that this is his last election, he has focused so narrowly and taken hardline positions on obscure issues, while leaving major issues like transportation up in the air,” said Neill Herring, a Sierra Club lobbyist who has spent more than three decades at the statehouse.

The governor may be reluctant to take charge of the controversial issue because he’s in a tricky spot with other legislative priorities. At the top of his agenda is another dicey prospect that he mentions at nearly every public event: a push to give the state new powers to take over failing schools that narrowly passed the General Assembly last week.

But he has also intervened on behalf of legislation that would give many top judges a 10 percent raise. And he has vigorously defended a bureaucratic switch that would give his office more control over a little-known state conservation agency.

Meanwhile, he’s been far more tight-lipped on transportation, which he has said he would leave to the legislative branch ever since a study committee began meeting last year to look at ways to generate money for roads, bridges and transit.

“It would be presumptive on the part of the governor to step in and try to undercut what that committee has done and the recommendations they produced,” Deal said in a recent interview. “I’m not the kind of governor that will do that. I recognize the role of the legislative branch, and I think they’re showing they can live up to their responsibilities.”

Taking charge, or taking a back seat?

The governor’s strategy is a sharp contrast with the approach taken by leaders in other states pondering ways to generate new revenue for infrastructure improvements.

Transportation for America, a national organization that advocates against sprawl, said it has not found any case where a state legislature was able to act to fund roads, bridges or mass transit without the governor’s support. Spokesman David Goldberg said the strength of that support has varied from overt advocacy to a mere indication of willingness to sign a bill.

“The process seems to go smoother and more quickly when the governor is actively championing than when he is a passive observer,” said Goldberg. “But the effort is certainly not doomed as long as the governor is indicating a willingness to sign ultimate legislation.”

Some governors more aggressive

South Dakota, South Carolina, Minnesota and Connecticut governors are among state leaders who have outlined specific plans, embraced tax increases and detailed the amount of money that needs to be raised.

In many cases a governor got the conversation started by introducing a self-scripted proposal, but the legislature ended up endorsing a dramatically different solution.

In Washington state, Democratic Gov. Jay Inslee is pushing a a $15 billion transportation package paid for in part by a charge on carbon polluters.

“We’re falling behind on maintenance, safety, traffic relief,” said David Postman, a spokesman for the governor. “He really felt it was incumbent upon him to lay out a specific plan not just on what needed to be done but how to pay for it long term.”

Despite the governor’s efforts, the Republican-dominated Senate in Washington passed a plan to increase the gas tax incrementally, by 11.7 cents over three years. The plan does not include aspects of Inslee’s climate-based proposal. The legislation is now before the Democratic-controlled House.

South Carolina is facing a similar divide.

Republican Gov. Nikki Haley this year has been championing a plan to raise the gas tax by 10 cents. She would offset that by lowering the state income tax — a so-called “tax swap.” But state lawmakers have rejected the tax swap idea, and the fate of the measure is in limbo.

Still, Haley’s advocacy for her transportation package has “probably helped to put it at the forefront of the agenda,” said Barton Swaim of the South Carolina Policy Council, a conservative think tank that opposes her plan. Swaim said Haley has at least helped raise public awareness of South Carolina’s underfunded transportation system.

‘There’s been a lot of frustration’

In Georgia, too, the House and Senate approved different versions of a transportation bill. Both would eliminate the combined sales and excise tax on gasoline and convert it to a straight excise tax on every gallon of fuel sold.

The House version seeks a tax of 29.2 cents per gallon, while the Senate wants a more conservative 24 cents. The dueling versions contain other differences affecting taxes or fees on a range of other items.

When there is legislative discord, that’s a time when a governor’s influence can count the most, according to Goldberg.

“If the House and Senate are in radically different places, it can be important,” explained Goldberg. “If the governor indicates either behind the scenes or publicly where he is likely to come down, that can help tip the scales and resolve the issues.”

In private meetings at his second-floor statehouse office, Deal and his top aides have sought to influence the debate in quieter ways. The tinkering even led Republican Rep. David Stover to accuse Deal of heavy-handed tactics that marginalize the legislative branch, though he didn’t mention a particular measure that stoked his complaint.

Charlie Harper, the director of the PolicyBEST advocacy group, predicted Deal could play a more vocal role in transportation now that he’s secured support for his sweeping schools proposal.

“There’s been a lot of frustration around the government. They wish he could be more engaged on transportation,” said Harper, who is also an analyst at the Peach Pundit blog. “And now with a few days left in the session, he has time to encourage them to come together on a bill that will allow Georgia to have a long-term solution.”

The Metro Atlanta Chamber, one of the most vocal boosters of the transportation plan, praised Deal’s role in the process. Katie Kirkpatrick, the chamber’s chief policy officer, said the governor has made clear he believes “that the time to address the state’s transportation need is now.”

‘Slow this train down’

Deal has had no shortage of voters calling on him to take action one way or another.

His office has received hundreds of emails and calls from local politicians, policy wonks and ordinary voters airing concerns about the measure or offering advice.

Consider the complaint from Brian Kish, a Butts County resident who urged the governor last month to “slow this train down” and consider the state’s options.

A few days later, Kish received a reply from the governor’s office. It urged him to take his appeal elsewhere.

“The members of the General Assembly in your district can actually sponsor or vote on legislation on your behalf.”