Republican Jerry W. Kilgore says he's the anti-tax candidate for governor. Yet he supports giving Northern Virginia and other regions the power to raise taxes for roads, a position that helped earn him the endorsement of the Fairfax County Chamber of Commerce last week.

Democrat Timothy M. Kaine vows to oppose all taxes for roads until a constitutional amendment locks up the state's transportation fund. But he, too, leaves the door open a crack, saying that something short of an amendment might allow for tax increases.

Each wants to make it clear -- crystal clear, in fact -- that he won't raise taxes if he is elected governor next month.

Yet both are willing, if not vocally so, to embrace the idea that taxes might just have to go up if that's what it takes to pay for roads, schools or other services that Virginians want.

In the complicated world of Virginia politics, where popular anti-tax sentiment often runs head-first into fiscal reality, Kilgore and Kaine are finding that it's not so easy to take black-and-white stands on issues that affect the voters' pocketbooks.

"There's probably a recognition there that people in both parties know we are going to have to raise some taxes to meet the transportation needs," said Bob Chase, executive director of the Northern Virginia Transportation Alliance, a pro-roads group. "But it's still the third rail."

State Sen. H. Russell Potts Jr. (R-Winchester), an independent candidate for governor, has leapt onto that rail. His main campaign proposal is to raise $2 billion or more a year through tax increases and tolls to pay for massive road, bridge, tunnel and transit projects. Like former presidential candidate Walter F. Mondale, Potts openly admits he would raise taxes.

Potts's position may be one of the things costing him support, political observers believe. Public opinion polls show him mired in the single digits while Kaine and Kilgore each garner about 40 percent of the vote.

With a month until Election Day, Kilgore, the former state attorney general, has gone on the offensive, trying to cast Kaine as a liberal with an insatiable appetite for higher taxes.

In a biting 30-second political commercial, a ghoulish cartoon rendering of Kaine gobbles up plates of money as an announcer says that "nobody chews up tax money like liberal Tim Kaine."

Kilgore spokesman Tim Murtaugh said that if Kaine "were true to his heart, he would come out and say, 'I am going to raise your taxes.' He is going to raise the gas tax at the earliest possible moment."

In fact, Kaine's position on taxes is more complicated than that, especially when it comes to gasoline.

Kaine, the lieutenant governor, said he is opposed to increasing Virginia's tax of 17.5 cents per gallon on gas and will veto any tax increases for roads until the state passes a constitutional amendment that prohibits lawmakers from using money in the transportation fund for other purposes.

"He says, 'Without a guarantee, I'm not talking about it,' " Kaine communications director Mo Elleithee said.

However, the soonest a constitutional amendment could go into effect would be 2009, leaving Kaine no option to increase taxes for transportation until nearly the end of a four-year term. Stung by criticism that his plan offers no immediate hope for new roads, Kaine provides himself an out.

He said he would consider raising taxes if lawmakers found an alternative to a constitutional amendment that would ensure the money was used only for roads.

What could that be? Kaine said he hasn't "thought through, necessarily, what all the mechanisms could be." But he said creative lawmaking might open the door to higher taxes for transportation as early as next year.

"We've got creative people in the legislature," Kaine told reporters recently. "If we look at all that money and the legislature says, or the business community, 'Hey, that's not enough,' I'll work in good faith to look for revenue. But they've got to agree with my proposition first to lock up the money."

On general taxes for schools and other state services, Kaine refuses to take a no-tax pledge. But he quickly said that tax increases passed last year will probably satisfy the need for revenue for a generation. He joked that taxes in Virginia are raised only on the "cicada cycle," referring to the flying pests that emerge every 17 years.

Kilgore's position on taxes starts from a seemingly rock-solid premise: He won't raise them.

He repeatedly says he would fight higher taxes. He often reminds voters that he opposed the tax increases that were part of the 2004 budget deal. And his attacks on Kaine are meant to emphasize his own anti-tax credentials with the state's voters.

But the promises Kilgore has made during the campaign will cost money, especially the many road and bridge projects he has pledged to build. Most transportation advocates say the projects couldn't be finished without a new source of revenue, even with a booming economy.

So Kilgore has given himself an out as well.

He said he would accept tax increases if they were the will of the public, passed in a voter referendum. And he promises to push legislation that would give regional transportation authorities the right to hold tax votes without getting prior approval from the legislature, as they are required to do now.

In a private interview with the Fairfax chamber last month, Kilgore promised that he would not oppose Northern Virginia's efforts to pass a tax increase referendum, according to several people who attended the session.

"It does give us an opportunity to generate new revenue streams if we do choose as a region to raise our own taxes," said Mike Lewis, a former chamber chairman and a member of its political arm. "His response was, 'I will not stand in the way.' That was very important for us to hear."