Virginia Attorney General Ken Cuccinelli on Monday backed a transportation plan that is being offered as a conservative alternative to a plan offered by Gov. Bob McDonnell, a fellow Republican who had intended to make transportation improvement his legacy.

The alternative package will be introduced by Senate Transportation Committee Chairman Steve Newman, who was previously tapped to carry McDonnell's $3.1 billion plan.

McDonnell proposes eliminating the state gas tax and increasing the sales tax and some registration fees to generate more money for roads.

The plan Cuccinelli is backing would not raise sales tax or any fees. It would convert the 17.5 cents-a-gallon gas tax to a sales tax that could rise with inflation. It wasn't immediately clear how much the sales tax on gas would be.

A similar proposal passed the Senate last year but died in the House.

"I hope legislators will join together to advance Sen. Newman's alternative," Cuccinelli said in a statement to The Washington Examiner. "The proposed sales tax on gasoline will replace a gas tax that is no longer the best means of raising revenue for transportation."

McDonnell's office said it is reviewing the Cuccinelli-backed proposal.

Cuccinelli is running to replace McDonnell, who had hoped to make solving the state's transportation funding problem his gubernatorial legacy.

McDonnell's plan is projected to raise $3.1 billion over five years, while the Cuccinelli-backed plan would raise $1.2 billion less. Both plans assume money that would be collected from taxing online purchases, but that needs congressional approval. They both also would shift general fund revenue now used on other state programs, including education, to roads, a change Democrats oppose.