Wisconsin Gov. Jim Doyle said a proposal to up the gas tax by 3 cents a gallon in his state was worth considering, even though the law would go against his 2006 campaign promise not to raise the gas tax in his second term, the Milwaukee-Wisconsin Journal Sentinel reported.

Doyle said the state probably should not have eliminated annual increases in the gas tax, even though he signed that change into law in 2005.

The governor’s preference is to tax oil companies rather than consumers, but that proposal is unlikely to gain approval in the Legislature, which is searching for money to pay for roads and close a $5 billion, two-year shortfall. The state needs a long-term plan for building funds for roadwork, beyond the $529 million in federal stimulus dollars it will receive and must spend on road work in the short term.

Doyle’s proposal would prevent oil companies from passing the tax on to consumers, which critics argue violates the U.S. Constitution’s protection of interstate commerce.

Convenience store owners and others are fighting Doyle’s plan through grassroots lobbying and legal memos warning that his plan would not survive a challenge in the courts. The convenience stores association has run ads against the proposal, calling it an “everyday Joe tax,” and has supported increasing the gas tax for consumers by 3 cents a gallon.

Wisconsin’s gas tax currently stands at 32.9 cents a gallon, among the 10 highest in the nation. The federal tax adds another 18.4 cents.

Other states also are considering significant increases in their gas taxes, including Massachusetts, which is debating a 19-cent increase in the gas tax.