Loudoun voters sent a strong message Tuesday that they are concerned about the pace of growth in the county, one that could result in yet another dramatic shift of direction for the Board of Supervisors when its members are up for reelection in 2007.

Then again, maybe voters didn't.

Perhaps Republicans just didn't turn out their base or independent voters were reacting to President Bush's all-time-low popularity numbers.

For the first time in 16 years, county voters supported a Democrat for governor, helping hand Lt. Gov. Timothy M. Kaine a victory over Republican Jerry W. Kilgore.

In Loudoun, where voters have swung back and forth between opposing and supporting rapid development, much of the election postmortem has centered on the role that might have been played by that perpetual debate.

After a year and a half of public debate, the Board of Supervisors voted in 2001 to erase 80,000 houses from county building plans. But in 2003, slow-growth advocates lost their majority on the board after the most expensive local election in county history. Since then, the Republican-led board has approved thousands of new houses and pushed to add tens of thousands more down the road.

Watching election returns on a large overhead screen at the County Government Center on Tuesday night, Board of Supervisors Chairman Scott K. York (I) declared that the election signaled another change in the mood.

York is a leading proponent of slowing growth and parted ways with the Republican Party over the issue. He said Kaine's decision to step into the debate in the final weeks of the campaign, running television ads promising to give local governments new tools to control home building, was the key to victory in Loudoun.

"No one's solving transportation, and yet we keep growing and growing and growing," York said. "Loudoun voters get the issue, and they want the problem solved. In two years, I think you'll see that's the case at the board level."

The day after the election, the regional advocacy group Coalition for Smarter Growth sent out a news release declaring, "Growth Issues Swing Gubernatorial Election."

"We heard many voters saying they voted for Kaine because of the growth issue," Laura Olsen, the group's assistant director, said in the release.

Local Republican leaders, however, were skeptical, suggesting a variety of explanations for Kaine's Loudoun victory: disillusionment with negative campaigning, unhappiness with national party politics and President Bush, an energized Democratic base that turned out while Republicans, uninspired by Kilgore's message, stayed home.

"I don't want to see everything boiled down, as it sometimes is, to growth politics," said J. Randall Minchew, chairman of the Loudoun County Republican Committee. "Frank Raflo, the former board chairman, once said that if you put any group of Loudoun County people in a room and say, 'Go talk about something, anything,' and you come back a while later, they'll be talking about growth politics. But there's more to political life in Loudoun County than that."

Minchew said his party lost because voters were turned off by Kilgore's hard-hitting ads about the death penalty and because they were not convinced that the Republican was offering solutions on such bread-and-butter issues as transportation and education.

"I think the basic core demographics of Loudoun show that we remain a Republican county," he said.

County residents, however, also endorsed Democrat Leslie L. Byrne, who was unsuccessful in her bid for lieutenant governor against state Sen. William T. "Bill" Bolling (R), and voters in the east backed Democrat David E. Poisson, who unseated four-term incumbent Del. Richard H. "Dick" Black (R).

Minchew said he did not think growth played significant roles in those races. If correct, that assessment would undercut arguments that growth was a major force in Kaine's election.

Poisson, however, said voters linked the quality-of-life issues he was talking about and rapid growth.

"It was a referendum about the need to be much more forthright about what the consequences are of unbridled growth," he said, adding that he was eager to work with Kaine on legislation on the issue.

Statewide, political pundits have concluded that Kaine's strong showing in populous suburban areas was the driving force behind his victory, even as he lost ground in some rural areas that supported Gov. Mark R. Warner (D) four years ago.

Several analysts have suggested that Kaine's entry into the growth debate did indeed pull voters, not just in Loudoun but also in Prince William County, which supported a Democrat for the first time since 1985, and in Fauquier and Stafford counties, where Kilgore won but by a smaller margin than Republicans in previous elections.

"I tend to think that was a big issue for Kaine," said Stephen Farnsworth, an associate professor of political science at the University of Mary Washington in Fredericksburg. "There's certainly a feeling among people who have been in these outer-ring communities that growth is occurring too rapidly and without enough planning and without enough support from developers."

Supervisor Stephen J. Snow (R-Dulles) said he did not hear voters talking about growth at any of the three precincts he visited Tuesday. He insisted that the supervisors elected in 2003 have successfully negotiated with developers to provide more land for schools and more money for transportation improvements. Critics charge that the new contributions do not keep pace with growth. Snow said that if growth is the debate in the 2007 elections, Republicans will carry the day again.

"For the first time in Loudoun County, we're actually managing growth," Snow said.

Board Vice Chairman Bruce E. Tulloch (R-Potomac) said he will support Kaine if he pushes to provide local governments more leeway to control growth. Tulloch said he was skeptical of the governor-elect's ability to make good on the campaign promise and move such legislation through the Republican-controlled General Assembly. As for 2007, Tulloch said there's a long time before the arguments can be put to the test.

"It's really easy for any politician to speculate on what will happen in two years," he said. "But they don't have a crystal ball to tell me what will happen even two weeks from now."