PHOENIX — The head of the House Transportation Committee is crafting legislation to double the state’s 18-cent-a-gallon gasoline tax.

Rep. Noel Campbell, R-Prescott, said Thursday he hopes to convince colleagues that the revenues from the current levy — about $750 million a year — are insufficient to meet the state’s needs, both for building new roads and maintaining the ones already in existence. He said it’s simple math: the tax rate hasn’t changed since 1991.

“A tax dollar in 1991 is worth 47 cents today,” he said.

Campbell conceded he likely has an uphill fight.

It would take a two-thirds vote of both the House and Senate to alter the tax. And even if he could get that, then there’s Gov. Doug Ducey who gets the last word.

“You know what my feelings are about taxes,” the governor told Capitol Media Services.

And Ducey, promoting the widening of 23 miles of I-17 between Anthem and Sunset Point, said the ability to finance that proves the state has all the money it needs.

Arizona’s $130 million share of the $300 price tag is coming from a surplus of state tax collections. That enabled lawmakers to put an earmark into the state budget for this specific project, outside the normal road-funding process.

Campbell acknowledged the point. But he said it would be wrong to presume that Arizona will continue to have $1 billion surpluses forever.

“You can’t count on a good economy over the years,” he said.

“It’s going to go up, it’s going to go down,” Campbell continued. “We just don’t have the money for new road construction.”

And that, he said, doesn’t even take into consideration maintaining existing highways and roads.

In promoting the widening project, Ducey said the main beneficiaries are going to be those seeking to get away from the state’s metro areas, at least for a time.

“On a busy weekend, I-17 sees more than 50,000 vehicles per day,” he said.

“And with this new expansion, I-17 will be less congested and safer than ever before,” the governor continued. “For families, that means more time in Sedona, in Prescott, all over northern Arizona and Coconino County and even Yavapai County, and even less time spent in traffic or stuck in accidents.”

But adding a third travel lane all the way to Black Canyon City could have another effect.

As daily travel becomes easier and faster, people may feel more comfortable living further away from their jobs in downtown Phoenix. But Ducey dismissed the concern that the project will lead to urban sprawl.

“We’re encouraging quality of life and safe travel and ease in commutes and traffic,” he said. Still, the governor acknowledged that people may move further from the urban core.

“Of course, with the fastest growing city, the fastest growing county in the nation, we’re going to have increased home building as well,” Ducey said. The governor said, though, not all of the growth is out, citing new mid- and high-rise construction in downtown Phoenix.

“It provides choices for the citizens,” he said of the opportunities for people to live further out.

“It’s not encouraging one or the other,” Ducey continued. “It’s allowing people to make a decision how they’d like to live and, at what stage of their life how to choose where they want to live.”

Aside from adding a third lane up to Black Canyon City, the project also includes a unique-for-Arizona plan for eight miles of “flex” lanes between Black Canyon City and Sunset Point, essentially two extra lanes separate from the existing northbound or southbound lanes.

John Halikowski director of the Arizona Department of Transportation, said these can be used to handle heavy northbound traffic on Fridays and southbound traffic on Sunday evening.

But the real benefit could be preventing the kind of multi-hour delays that occur when there is a serious or fatal accident on that winding stretch and state police cannot immediately clear the road. Traffic could then be diverted to the two extra lanes separate from where the accident occurred.

The ability to finance this specific project still leaves Campbell uneasy about future needs.

He said the issue isn’t just building new roads.

There’s the question of the state’s ability to maintain the ones it already has. And with inflation-adjusted revenues at 47 percent of what they were in 1991, he said, that just isn’t possible.

Campbell said there is support among many sectors of the Arizona economy to increase the levy.

“It is to benefit the economy of the whole state,” he said. “The trucking industry, the manufacturers, the League of Cities and Towns, County Supervisors Association, they all support it.”

That, however, isn’t the problem.

“When it gets up to the Legislature it meets a roadblock,” Campbell said.

“It’s a difficult issue for these members to have to vote on increasing fuel taxes, user fees, when they’re up for election,” he explained. “And I understand that.”The record backs that up. Campbell and other supporters of increased road revenues have had some success in prior years in getting various plans approved at the committee level only to have the legislation stall, sometimes because the chair of another committee refuses to give it a hearing.

There is another option: Take the issue to voters.

It would take only a simple majority of the House and Senate to refer the question to the 2020 ballot, versus the two-thirds vote for lawmakers to increase the levy themselves. Potentially more significant, the governor cannot veto a ballot referral.

And if lawmakers balk at even that, there is still the possibility of gathering the signatures for an initiative.

He said there is some reason to believe voters can be convinced to approve higher taxes if it means better roads. He cited the experience in several counties which have approved sales tax hikes for roads and mass transit.

Campbell said his plan would not let those who drive alternate fuel vehicles who also use Arizona roads off the financial hook. He said it would include some sort of fee that would be relatively equivalent to what would be paid by a typical motorist driving a gasoline-fueled vehicle.