When Timothy M. Kaine walked into the Leesburg airport terminal yesterday, the next governor of Virginia stepped straight into a political upheaval that shows how tough it will be to fulfill his campaign promise to fight snarled traffic by better managing development.

Following a stop earlier in the day in Fredericksburg, Kaine (D) brought his transportation listening tour to the heart of Northern Virginia's home-building boom, where frustration about the effects of swift growth helped put Republican-leaning Loudoun County in Kaine's camp in last month's election.

More than 200 politicians, activists, development industry representatives and residents stood and sat in rows around Kaine for the loose and cordial session in the terminal building. He listened to commuting horror stories and an assortment of sometimes dueling pet priorities -- such as those for and against extending Metrorail to Dulles International Airport -- and said he's eager to make a speedy impact.

"I was a mayor," Kaine said, adding that the last time voters put a local elected official in the governor's mansion was in the 1930s. His experience heading Richmond, he said, enables him to understand the importance of empowering localities when trying to solve pressing transportation problems. "It's got to be urgent," he said.

That intimacy with local government could prove helpful to Kaine in dealing with the politics and congestion of places such as Loudoun. Kaine appeared at a pivotal political moment in the county, which has grown faster since 2000 than any other county in the country, according to the U.S. Census Bureau.

Republican members of the Board of Supervisors who once voted as a bloc for policies that would spur construction are now sometimes divided, tipping the balance in a number of key votes toward those who favor tighter controls and sparking fierce debate.

Moreover, politicians are already positioning themselves to run a crash campaign for a state Senate seat they believe could be up for grabs within weeks, fueling an already intense power struggle within the county.

Republican officials believe Sen. William C. Mims (R-Loudoun) is likely to resign his 33rd District seat to take a job with Republican Robert F. McDonnell -- if McDonnell survives a recount in his tight race for attorney general. McDonnell was certified the winner last week with a margin of 323 votes. Mims would not say whether he plans to resign.

"We have an attorney general-elect who is a close friend of mine, and my focus right now is on ensuring that there is a fair recount. I hope and expect he will become our next attorney general," Mims said. "Other than that, I'm not going to comment presently."

Supervisor Mick Staton Jr. (R-Sugarland Run), a key proponent of increasing home building in Loudoun, and former Democratic supervisor Charles A. Harris, a growth-control advocate, say they will run for the seat if Mims steps down. Others are also exploring a bid, people from both parties said.

Kaine said yesterday that he has been eyeing the situation carefully and considering what role he might play. "I'm certainly pondering that," Kaine said after the session ended. "The right time for that is if Senator Mims makes an announcement."

During the public give-and-take yesterday, Kaine did not respond directly to local officials who asked him to fulfill pledges to push for more direct links between transportation and land-use controls. "A lot of us are looking forward to you following through with your campaign promises," said Supervisor James Burton (I-Blue Ridge), who has been rebuffed on several occasions when he asked the General Assembly for additional powers to regulate development.

Kaine said in an interview that he would urge the General Assembly to give localities clearer authority to turn down some applications to build subdivisions if transportation is insufficient.

"It's been tough," he acknowledged. But, he added, "it's an idea whose time has come."

The traffic congestion that so animates political debate and irks residents in locales such as Loudoun defies simple solutions. In a time of bogged commutes, booming home building and tight budgets, facing the future of traffic is often an exercise in counting minutes.

A three-mile stretch of Route 7, a heavily traveled thoroughfare cutting through Loudoun and Fairfax counties and beyond, offers a glimpse into the challenges Kaine and local officials face in trying to shape that future.

It currently takes a morning rush hour commuter five to seven minutes to travel east from Countryside Boulevard in Loudoun to Dranesville Road, just inside the Fairfax line. The trip, past a series of strip malls and residential communities, includes eight intersections with traffic lights.

But after a decade of further growth, it will take between 13 and 15 minutes to travel the same distance, according to a Virginia Department of Transportation study made public last week.

With a series of modest improvements -- which would cost more than $1.8 million and include altering turn lanes and encroaching on medians -- commuters would be left with a nine- to 11-minute trip in 2015. That's considerably longer than it takes today, but shorter than it would be if nothing is done.

Some much more dramatic investments would still not neutralize the effects of projected growth, according to the VDOT study. For instance, building an interchange at Potomac View Road and a flyover at Sterling Boulevard would cost $104 million and would increase road capacity by only 15 to 20 percent. That would mean that by 2015, even after a massive infusion of cash, it would still take more than a minute longer than it does today to travel that three-mile stretch.

Kaine addresses such concerns about the financial and physical limits of focusing solely on constructing road improvements. "There's no way to just tax and pave our way out," he said.

Virginia Gov.-elect Timothy M. Kaine speaks at a transportation meeting at Leesburg airport yesterday, where he heard commuting stories and suggestions from politicians, activists, developers and residents.