Virginia Gov. Bob McDonnell must decide by midnight Monday whether to sign, veto or amend legislation that would raise roughly $1 billion a year in new taxes and fees to pay for long-delayed road work in the state.

The transportation package is one of hundreds of bills on which McDonnell must act, including the budget, a voter ID bill and a two-year moratorium on drones flying in state airspace. But for a governor harboring national political ambitions and with an undefined legacy, the transportation package is the most important bill on his desk. And it's one that his own attorney general, fellow Republican Ken Cuccinelli, is fighting to defeat.

Cuccinelli, who is running for governor, said a critical provision to raise the sales tax in Northern Virginia and Hampton Roads higher than the rest of the state is unconstitutional. Residents in those two areas would pay 6 percent but would keep the additional $500 million in revenue over the next five years for their own road projects. Most Virginians would pay a 5.3 percent sales tax.

McDonnell must now weigh whether to change the bill to allow localities in those regions to raise the sales tax higher on their own.

"If he did that, he might as well go ahead and kill the bill," said Del. Dave Albo, R-Springfield. "Then you have freeloaders. You get counties like Prince William and Loudoun that won't vote to raise taxes but drive on Fairfax roads."

McDonnell is playing his cards close to his vest. While he initially praised lawmakers last month for pushing the bipartisan road plan through the General Assembly, the Republican leader has since taken an earful from opponents within his own party. One conservative group ran ads against him in the early presidential primary states of Iowa and New Hampshire.

It's clear that the bill will define McDonnell's legacy, but will it be that of a man who fixed the state's congestion woes or the Republican who raised taxes?

"Time heels a lot of things," said Del. John O'Bannon, R-Richmond. "I never quite understood how [former Gov.] Mark Warner's raising the sales tax made him as durable and popular as it did, but it appears to have done that. McDonnell's got a great track record. This will be a piece of it."

Supporters of the bill are hoping McDonnell leaves it as is. In addition to raising the sales tax, the bill would replace the gas tax with a tax on wholesale gas and make it more expensive to buy a car, sell a home and stay a night in a hotel.

"There's a lot of people who took a difficult vote who would be upset if he made fundamental changes," said House Minority Leader David Toscano, D-Charlottesville.

But opponents said McDonnell should at least address the constitutional concerns Cuccinelli raised.

"If he wants it to be even enacted," said Sen. Steve Martin, R-Chesterfield, "he has to get rid of what would be challenged in courts."