The proposal to build a 10-mile road between Prince William and Loudoun counties is spurring lots of debate, but it’s not clear how the wave of opposition will affect plans for the so-called Bi-County Parkway.

Last week, opponents of the project turned out in Fairfax for a meeting on regional transportation priorities, and that was just a curtain raiser. On Monday, more than 450 people — including one holding a sign reading “Why railroad a bypass?” — streamed into the Hylton Performing Arts Center in the Manassas area for a meeting with state officials.

And on Tuesday, the Prince William Board of County Supervisors voted unanimously to strip the parkway from the county’s list of state road priorities. The move was a nod to opponents, though far from final. Board Chairman Corey A. Stewart (R-At Large) said the vote was “not good” for the parkway’s prospects, but he noted that the road, which he supports, remains on the county’s long-range comprehensive plan.

Supervisor Peter K. Candland (R-Gainesville) said he did not want controversy over the parkway to hold up the rest of the county’s primary road priorities, such as widening sections of Interstate 66 and Route 1. “I cannot remember a road [being built] in my lifetime where it has gone against so much opposition across the board from the people who actually live within the affected county,” Candland said of the parkway.

Virginia Department of Transportation spokeswoman Joan Morris emphasized that the parkway is “not out of their long-range plan — it’s out of their wish list for this year. ” She said the Commonwealth Transportation Board will decide whether to allocate money for the project. Transportation Secretary Sean T. Connaughton, chairman of that board, was not available to comment, she added.

Among those fighting the road are Rick Gutierrez, who told state transporation officials Monday that their proposal was “immoral” and amounted to theft. The road would barrel across his family's property and destroy their “utopia,” he said.

“There’s not a lot of eight-and-a-half-acre wooded land in Prince William County near Fairfax. We picked that dream location so we can build up on it,” Gutierrez said after the meeting. “The primary purpose of government is to protect inalienable rights. . . . Thomas Jefferson didn’t just make that up.”

On Monday, a top VDOT official walked through some of the state’s reasons for supporting the road plan. Population and jobs are expected to grow for decades in the region, and a new parkway is just one among an array of ideas meant to address bottlenecks across Northern Virginia, VDOT Deputy Commissioner Charles Kilpatrick said.

Afterward, many people remained steadfastly opposed to the plan while others wrestled with the claims, counterclaims, building plans and traffic projections.

“If nothing gets built, it gets worse. I buy that part of the presentation,” said Charles Gibbs of Gainesville, a government teacher who commutes to Chantilly. “I just don’t see how this would be an effective remedy. I’m trying to ascertain whether it’s going to worsen it or not. It’s unclear.”

Opposition came on many fronts: Owners of property in the path objected. Other residents were angry that changing the road network could send commuters pouring onto their own narrow roads. Still others worried about plans to build a bypass for routes 29 and 234, after which those roads would be closed off to through traffic within Manassas National Battlefield Park. They said that change could worsen their commute toward regional job centers in Fairfax County and further east toward the District.

Transportation officials said that they are unable to expand the already-clogged road network within the park and that traffic will only get worse. The new parkway and battlefield bypass would help in the long run, they said.