A proposed 1-cent hike in state sales taxes doesn't devote enough money to mass transit, the Sierra Club says, and the group is urging voters to defeat the measure.

The environmental group said Thursday that only 18 percent of the $42.6 billion that would be raised during the next 30 years from the new levy would go to more buses and light rail. And Jim Vaaler, who chairs the organization's Grand Canyon chapter, said the club is particularly interested in proposed Tucson-to-Phoenix passenger rail service.

Thursday's announcement creates a second front of opposition for the business and civic groups that hope to persuade voters to increase the amount of taxes they pay on most items they purchase.

The Arizona Federation of Taxpayers says the plan actually spends too much on what Chairman Tom Jenney calls "highly expensive and ineffective transit projects such as light rail."

And state Rep. Russell Pearce, R-Mesa, is exploring whether to put an alternative plan on the November ballot, one that would hike the state's 5.6 percent sales tax by just half a cent, with all of the money going to new and expanded freeways and roads.

Vaaler said 55 percent of the cash raised would go to state highways, mostly in Maricopa and Pima counties. He said that makes little sense, as both counties already levy sales taxes for transportation, with most of those dollars earmarked for roads. He noted that none of the proceeds from Arizona's 18-cents-a-gallon gasoline tax go to mass transit projects.The Sierra Club also was particularly upset the tentative plan includes new roads in the area from Chino Valley through Prescott Valley to Dewey.

"This will not only subsidize more sprawl in an area already fighting over diminishing ground water, but will also fragment one of the last, best Pronghorn grasslands,'' said Tom Slaback, who chairs the club's Prescott area group.

The group also took aim at a deal cut by Gov. Janet Napolitano with the Home Builders Association of Central Arizona. Napolitano agreed that the proposal that would be put on the ballot would rely solely on hiking sales taxes, with no "impact fees'' or other new charges on developers.

Vaaler said that runs contrary to the Sierra Club's belief that growth should be "paying its way in Arizona.''

Napolitano has defended the deal. She said it ensures not only that homebuilders will not oppose the tax hike but actually requires the group to provide $100,000 to help finance the campaign to get more than 153,000 signatures on petitions by July 3 to qualify for the November ballot.

As part of the deal, the homebuilders also agreed not to oppose another initiative sponsored by the Nature Conservancy to put 570,000 acres of state trust lands permanently off limits to development. Opposition from the group to a similar plan two years ago helped lead to its defeat.

So far, most of the money for the road tax plan has come from companies who could benefit from major new spending on road and transit projects. That includes $100,000 from Combs Construction Co., $35,000 donations each from Ames Construction Co., Haydon Building Corp., FNF Construction Co. and Pulice Construction; $30,000 from Achen-Gardner Engineering Corp., and $25,000 from The Sundt Companies.