Activists say they are targeting a portion of the state's new gas tax law that automatically links future tax hikes to increases in the rate of inflation.

Backers of a proposed ballot question say tying tax hikes to the cost of living creates what they call a ``forever tax'' that automatically rises without lawmakers having to take future votes.

Under the law pushed by Democratic leaders in the Massachusetts House and Senate and signed by Gov. Deval Patrick, the gasoline tax jumped 3 cents last week, from 21 cents per gallon to 24 cents, as part of a transportation financing package.