If approved, Question 1 on the November ballot wouldn't lower the state's gas tax, but it could stop future increases that would otherwise occur automatically and without any say by lawmakers.
Supporters of the initiative view that as a clear-cut case of "taxation without representation." But those urging a no vote on the question warn that passage would seriously undermine progress in fixing crumbling state infrastructure.
At issue is a provision in a 2013 transportation financing law that indexes the gas tax to inflation - meaning that as the Consumer Price Index rises, so does the tax. The group seeking to repeal the provision says taxes should never go up without a recorded vote by the Legislature.
Such votes, however, are politically dicey. Last year's move to raise the state gas tax 3 cents, to 24 cents per gallon, marked the first time in more than two decades that lawmakers increased the tax, which pays for maintaining roads and bridges.
"We are already woefully underfunded when it comes to our transportation infrastructure and we are already running way behind when it comes to funding it," said Mary Maguire, director of public affairs and legislative affairs for AAA Southern New England.
Indexing is "the most effective way to catch up," added Maguire.
State transportation officials estimate that indexing will produce an additional $1 billion in revenue over the next decade, and opponents of repeal suggest that would come at a nominal cost to consumers. Based on recent CPI trends, Maguire said an average motorist would pay only about $5 to $10 more per year at the pumps if the tax is indexed.
Those estimates understate the real impact, argues State Rep. Geoffrey Diehl, a Whitman Republican who co-chairs the group Tank the Automatic Gas Tax Hikes.
Prices for food and other consumer goods would rise, Diehl said, as shipping costs go up with higher gas taxes. Property taxes could also be affected as cities and towns pay more to operate police cars, fire trucks and other vehicles, he added.
Question 1 backers also object to tying the gas tax to the CPI, since gas prices are a key component of the CPI in the first place.
"It's rigged to go only one way and never in favor of the taxpayer," said Diehl.
Opposition to the ballot question has united environmental groups with business-backed organizations such as the Greater Boston Chamber of Commerce and Massachusetts Competitive Partnership. The No on One Committee raised $1.4 million through Oct. 1, according to filings with the state Office of Campaign and Political Finance, dwarfing the $87,000 raised by proponents.
Firms that contract with the state to perform road and bridge maintenance have been a major source of funding for Question 1 opponents.
More than half of the state's bridges are structurally deficient or functionally obsolete, said Maguire, who pointed to the recent shutdown of a bridge to Boston's Long Island, forcing a homeless shelter on the island to close.
Diehl suggests the state could spend more on road and bridge maintenance by cutting administrative costs instead.
Including all state and federal taxes and fees, Massachusetts drivers pay a total of 44.9 cents per gallon in gasoline taxes, according to the American Petroleum Institute. That puts the state below the U.S. average of just under 49.3 cents per gallon in total taxes.
Only a handful of other states, including Maryland and Florida, currently index their gas taxes, according to the institute.
Rhode Island lawmakers recently approved a plan for indexing the tax every two years, while the New Hampshire Legislature voted to raise the state's gas tax 4 cents per gallon, but without indexing.