The promise was first unveiled in a television ad, with an enthusiastic Timothy M. Kaine sitting behind the wheel of a moving car.

"I'll give your community more power to stop out-of-control development that increases traffic," the Democratic candidate for Virginia governor in the Nov. 8 election says during a 30-second clip that has been playing in Northern Virginia and Hampton Roads for more than two weeks.

Kaine, the lieutenant governor, says he would enhance local governments' power over zoning by allowing county boards and city councils to reject development plans if roads in the area are too congested to support them.

It's a key component of Kaine's plan to help reduce traffic in the Washington suburbs. And it's a direct parry to Republican Jerry W. Kilgore's proposal to create regional transportation authorities.

But here's the catch for Kaine:

Because Virginia operates under the Dillon Rule, a legal doctrine that gives local governments only those powers specifically granted by the state, the legislature in Richmond would have a lot to say about whether Kaine could deliver on his promise. Efforts to expand the power of local governments have met strong resistance in the General Assembly.

In Maryland, by contrast, localities generally have much more authority to balance transportation and development. They may institute "adequate public facilities" ordinances, which establish standards for services and allow local governments to curtail developments when those standards cannot be met.

For years, lawmakers from Virginia's quickly growing suburbs have tried to bring home more power for their local governments so they can exercise similar control over development.

One such effort came to a head in 2003 when Del. Robert G. Marshall (R-Prince William) and state Sen. Leslie L. Byrne (D-Fairfax) introduced bills that would have allowed rapidly growing jurisdictions with more than 55,000 people to "defer the approval" of subdivision site plans when local officials determined that "existing schools, roads, public safety, sewer or water facilities are inadequate to support the proposed development."

General Assembly committees rejected both proposals by large margins.

Marshall attributed the defeats to senators on the Local Government Committee and House delegates on the Cities, Counties and Towns Committee who were swayed by the protestations of developers and home builders -- a powerful lobby in Richmond -- who have vehemently opposed such bills requiring adequate public facilities.

"Moses could come before the Cities, Counties and Towns Committee and come back with empty tablets," Marshall quipped. He said he has tried to get similar efforts before other House committees as well, but they have been referred back to the same unfriendly panel.

Kaine's effort, he said, "is going to have a hard time, if it goes before that committee."

Kaine's staff has argued that because his plan seeks to create a standard for transportation only, rather than a wider variety of services, it may have a better fate.

"Localities should not be compelled to accept large new developments that overwhelm the local road infrastructure unless there is a funded infrastructure plan in place," the Kaine plan declares.

But even a more modest measure introduced in 2004 to give the city of Suffolk the authority to link development with school services was tabled in the Senate Local Government Committee. That was after a legislative group was created to help find common ground between the various interests. The group has since disbanded.

Several representatives for home builders and real estate brokers said they believe Kaine's plan would halt house construction and hurt the state economy. Others said the plan would push home building farther from Washington, into West Virginia and past Fredericksburg, and still clog roads.

They said they would probably fight Kaine's plan with the same intensity that they have shown in fighting other bills to give localities such authority.

"I can assure you we intend to oppose the measure if it does come up," said Schaefer Oglesby, chairman of the board of trustees for the Virginia Association of Realtors PAC, an organization that lobbied against the Marshall and Byrne bills. The group has endorsed Kilgore.

As for previous efforts to give localities more control, Oglesby said such attempts as the Marshall and Byrne measures were essentially "no growth" bills.

Some advocates who work to alter Virginia growth patterns said that, if elected, Kaine could capitalize on his leadership role and galvanize public support through the bully pulpit. They said public sentiment generally has favored their efforts.

"There is cause for optimism," said Stewart Schwartz, director of the Coalition for Smarter Growth. But he added: "The development interests are still very powerful at the state level."

In a television ad, Democratic gubernatorial candidate Timothy M. Kaine promises to "give your community more power to stop out-of-control development that increases traffic."