The Gilmore administration is signaling support for a referendum in Northern Virginia that could lead to a new local income tax to pay for transportation projects, state officials and lawmakers said today.

Aides to Gov. James S. Gilmore III said recent, intense lobbying by a trusted fellow Republican, J. Kenneth Klinge, of Alexandria, has helped persuade key staff members to rethink their opposition to permitting some of Virginia's most congested jurisdictions to hold a vote on new taxes for transportation improvements.

If Gilmore softens his steadfast opposition to any new transportation taxes, as senior advisers say he may, it could be a breakthrough for legislators struggling to find highway funding solutions among a thicket of proposals.

In cracking open one door to a locally approved income tax, the administration has slammed another shut on proposals such as a regional gasoline tax to pay for new roads, as some business groups and Democrats are proposing.

"That's going nowhere," said M. Boyd Marcus Jr., Gilmore's chief of staff.

The local income tax is a financing option that suburban counties have had for more than a decade but never used. Marcus suggested in an interview that Northern Virginia must exhaust every financing option it has, including the 1989 law enabling localities to put income taxes to the voters, before coming to the administration with hat in hand.

"It's difficult to talk about new sources of revenue when you haven't used one that's already on the books," Marcus said.

Del. James M. Scott (D-Fairfax), has filed legislation revising the old authorizing legislation, allowing Alexandria and the counties of Arlington, Fairfax, Loudoun and Prince William, as well as Norfolk, to ask their voters whether they want a new 1 percent levy on their Virginia taxable income. Local jurisdictions would be required to hold a referendum by July 2001.

"This is a use-it-or-lose-it bill," Scott said today. "The state has been blaming localities for not using their power, and localities have been blaming the state for not being able to.

"It does not grant any new authority," Scott said.

Scott's bill is designed to provide $429.6 million annually to cover the debt service on bond issues that would pay for the kind of massive projects Northern Virginia says it needs.

Scott said the "big correction" in his measure would be removing the legal barrier against new bonding authority that localities contend has constrained them for years.

Yet, a thousand practical and political problems remain, according to supporters and opponents of Scott's bill.

A provision to earmark some of the new money for education could be a trouble spot, as could a "sunset" clause killing the law if no county exercises its new authority within 18 months. Beyond that are the political problems of first holding a referendum on a possible income tax increase, then approving the bonds it would fund.

"There is no Plan B," said one of the region's veteran transportation lobbyists, alluding to the complexities of passing a referendum.

The biggest handicap for Scott's bill probably is the strong anti-tax climate in Virginia that Gilmore helped foster three years ago, with his insistent call to abolish the car tax. Northern Virginia business groups such as REGION, which has endorsed the local income tax idea in the past, are divided about Scott's measure, and conservatives here and in the Washington suburbs are poised to pounce on it.

"I'll confront it directly," said Peter Ferrara, of McLean, a spokesman for the Coalition of Virginia Taxpayers who is traveling to Richmond on Thursday for an anti-tax news conference at the Capitol.

"Why is there any need to raise taxes at all?" Ferrara said today. "Let's put some of this soaring increase in state revenues toward transportation."

In recent months, Gilmore has discussed Northern Virginia's local option, complaining that the region never exercised it even as it appealed for billions of dollars in state aid. At the same time, he has publicly disparaged the idea of a higher tax burden for roads.

Said Mark A. Miner, Gilmore's press secretary: "It does not become policy without the governor's signature. And he generally opposes any tax increase."

However, Gilmore's advisers do not believe he would suffer any damage whatsoever if counties voted to reject higher taxes for transportation.

Key members of the governor's team said they are listening to Klinge, 61, an experienced Republican campaign operative whom Gilmore named to chair a prestigious statewide commission on transportation funding.

Klinge has a resume that goes back 30 years in state politics, as a lowly executive director of the state GOP who rose through the ranks to become an adviser to U.S. Sen. John W. Warner (R), a player in the national party, an expert on airport policy in the Washington area and an architect of proposed solutions to the Washington region's transportation problems.

In the past year, Klinge has sought to balance the conservatism of Gilmore and the evident needs of his home region, inserting into every official analysis he can a reference to Northern Virginia's option for a local income tax increase.

"Let's have the public policy debate," Klinge said in an interview last year after Gilmore devised his own $2.5 billion transportation plan, which the General Assembly is now furiously rewriting.

"Let's put it to the voters and find out whether transportation really is the priority everyone says it is," Klinge said.

CAPTION: GOP campaign operative J. Kenneth Klinge, of Alexandria, is pushing to allow jurisdictions to have referendums on a local income tax.