Northern Virginia voters soundly defeated a regional transportation tax yesterday that opponents said would have funded suburban sprawl and forced families to pay more to governments they already distrust.

Voters across a political spectrum -- from liberal Democrats inside the Capital Beltway to rural Republicans in Loudoun County -- said they doubted that state and local governments would carefully manage the $5 billion that the tax would have generated for roads and mass transit over the next 20 years.

"I don't trust where the money will go," said Mike Weilmuenster, 59, of Springfield.

The defeat of the half-penny increase in the 4 1/2-cent-per-dollar sales tax was a stinging loss for Gov. Mark R. Warner (D), who had campaigned tirelessly for passage, and for Northern Virginia developers who had bankrolled the proponents' $2.5 million campaign against poorly funded opponents. A similar sales tax increase in Hampton Roads, which Warner also had championed, lost by an even greater margin.

"A host of voter concerns surrounding the two regional transportation measures led to their ultimate defeat," Warner said. "While these solutions have been rejected, I now call upon those who opposed them to help us find workable solutions."

The Northern Virginia vote was striking not only for the depth of resistance but also for the breadth. The tax proposal was crushed in conservative rural precincts outside the Beltway; in the urban centers, where advocates needed big wins, they eked out only the barest majorities.

Proponents expected to run up their margins in Alexandria and Arlington, but they ended up essentially tied with opponents in those two jurisdictions.

In statewide contests, Virginians elected U.S. Sen. John W. Warner (R) to a fifth six-year term and approved bonds for college construction and parks totaling just over $1 billion. Voters also approved a state constitutional amendment giving the Virginia Supreme Court new authority to consider DNA and other scientific evidence from felons appealing their convictions.

Incumbents in all four Northern Virginia congressional races won reelection. Republican Reps. Frank R. Wolf (10th District) and Thomas M. Davis III (11th) easily defeated little-known opponents; Republican Rep. Jo Ann S. Davis (1st) was unopposed. Democratic Rep. James P. Moran Jr. (8th) defeated Republican Scott C. Tate.

In a special state Senate race that was a kind of tax referendum in miniature, Republican Del. James K. "Jay" O'Brien Jr. easily defeated Democrat Rosemary M. Lynch and helped turn out GOP tax opponents in key precincts of Fairfax and Prince William counties.

On the surface, the Northern Virginia sales tax fight was a confrontation between mismatched adversaries: a bipartisan coalition of proponents led by the governor and Virginia's senior senator facing a sometimes uneasy alliance of anti-tax Republicans and environmentalists.

However, what the opponents lacked in formal organization, they claimed in grass-roots hostility to all tax increases, unease about creeping sprawl and deep-seated skepticism about government's ability to spend revenue prudently.

"I still have my doubts on whether these funds would be used the way they should," said Sam East, 45, a lawyer who lives in Alexandria. East said he voted no because "it sounds great in theory, but I'm not so sure I felt comfortable enough to vote for it."

In interviews, many voters across the region said they feared that money generated by the tax would be diverted, most probably by the General Assembly that has worked with Gov. Warner this year to close budget shortfalls that ultimately may total nearly $6 billion.

"We could vote for it, and it could all go to southern Virginia," said Jill S.P. Watkins, 32, of Manassas. "There's no guarantee."

Reinforcing those suspicions was the widely held perception -- especially in outlying areas such as Loudoun -- that the sales tax would benefit real estate developers before commuters and reward land-use policies that had favored commercial building over the preservation of open space.

"Who are the supporters of this? The developers," said Mary Metcalfe, 73, of Leesburg. "The multimillionaires who have become multimillionaires over the last 30 to 40 years through their land sales. And now they want to move on outwards by having us put in the roads."

Closer to Washington, in Fairfax and other jurisdictions that experienced steep rises in house assessments this year, feelings against additional tax burdens ran high.

"If we are paying such high taxes, they should be able to do it without this tax increase," said Mary Crowley, 70, of Arlington. "I don't know where all of that money goes, but someone is not using the money in the right way."

Said Brandon Quesnell, 27, of Arlington: "I think we get taxed enough already, and I don't think a half-cent will contribute that much to roads."

Proponents from all corners of the region said they were flabbergasted by the strength of yesterday's vote, coming a year after Warner embraced the referendum concept during his gubernatorial campaign. He and supporters in the General Assembly pushed the measure through in this year's session, setting up the vote.

Bob Chase, president of the Northern Virginia Transportation Alliance, said the issue was too complicated to present accurately to voters in such a short period of time.

"There were just a lot of nuances that couldn't be dealt with in a short campaign," Chase said. "I think all the opposition had to do in this campaign was raise doubts."

Among demoralized advocates, there was near-universal agreement that there was no fallback plan to pursue, either legislatively in Richmond or in the region through local governments.

Sen. Warner cautioned that the federal government is unlikely to provide money to fill the transportation funding gap. "It's just not there," he said.

Fairfax Board of Supervisors Chairman Katherine K. Hanley (D) called the defeat "a tragedy for transit in the region."

"Defeating the referendum hasn't made our traffic problems go away," said Linda D. Rabbitt, chair of the Greater Washington Board of Trade and president of Rand Construction Corp. in Arlington. "So we'll go back to work tomorrow to figure out how to solve them."

But Raymond G. Pelletier Jr., chairman of Public Private Solutions Inc. and a supporter of the measure, predicted that efforts to raise the sales tax in the region to address transportation problems were dead.

"People weren't in enough pain," Pelletier said. "They weren't in enough pain to buy this package. . . . Nothing will happen for a decade."

Meanwhile, slow-growth advocates and anti-tax activists said the region's political establishment should heed the vote's inherent warning against sprawl and additional taxes. Most of all, opponents said, elected officials need to show some respect for the desires of their own constituents.

"The Mark Warners, delegates and senators say that ideology and belief don't matter," said John Clerici, an Oakton Republican and referendum measure opponent. "But they do."

"And grass roots matter," he said.