Plans by Virginia transportation officials for a parkway that would link Prince William and Loudoun counties are being made with a “lack of transparency” and could open up preserved land near the historic Manassas battlefield to development, Rep. Frank R. Wolf (R) said in a letter this week to Gov. Robert F. McDonnell (R).

Wolf also said that Dulles Airport would not benefit from potential increased cargo traffic produced by the new thoroughfare — a key part of the state’s reasoning for the 10-mile parkway that would go through historic Manassas battlefield land and connect Interstate 66 in Prince William to Route 50 in Loudoun.

The so-called Tri-County Parkway, which for now would travel through two counties, deserves more time and study, Wolf wrote. The Commonwealth Transportation Board, which oversees the Virginia Department of Transportation, discussed the issue at a meeting Wednesday.

Wolf said the state should develop a “cost-benefit analysis” of the road and other potential projects to improve transportation congestion before moving forward.

The congressman echoed a number of concerns of the parkway’s detractors, including that it would open up Prince William’s protected Rural Crescent to development; that it would be paid for in part with tolls; and that it would undermine legislation Wolf shepherded in 1988 that would allow for Route 234 at Route 29 to be closed through the Manassas battlefield and a bypass built to avoid hallowed Civil War grounds.

“More public hearings must be held and more citizen input must be received before any final decision is made,” Wolf wrote. “I have seen the reaction of Prince William residents. What will Loudoun’s residents say as planning continues?”

Wolf said in an interview that Dulles officials — an airport he said he has long championed — told him that the McDonnell administration’s claims that the airport would be a primary beneficiary of a new four-lane parkway are not true. “Believe me, every time there’s a problem with the airport, they come here,” he said. A spokesman for the Metropolitan Washington Airports Authority, Christopher Paolino, said late Tuesday that the authority would review the letter.

Wolf said he wrote the letter to make his views known and that he has not planned any other action. He also said that no one should read anything into his criticism of a fellow Republican.

“This is not a Republican or Democrat issue,” Wolf said. “I represent those people. I was the one who led the effort to save the Battlefield.”

Jeff Caldwell, a spokesman for McDonnell, said in an e-mail that the bypass around the Manassas battlefield has been studied for 25 years.

“A 25-year-long study is definitely not on the fast track,” Caldwell said. Other studies, including a Dulles cargo study, continue, and both Prince William and Loudoun have included the parkway as part of their long-range planning documents, he said.

“We welcome the Congressman’s involvement and participation in the process,” Caldwell said.

Virginia Transportation Secretary Sean Connaughton could not be reached for comment. He and other supporters of the project, particularly the Loudoun and Prince William business communities , say the road would create jobs and drive area economic development, ease congestion and provide a key connection between two rapidly growing counties.

Wolf is the latest Republican to voice opposition to the parkway. Six Republican state legislators announced last month that they oppose the road for many of the same reasons as Wolf.

The parkway’s opponents have become increasingly worried about the road’s renewed prospects given new dollars for transportation made possible through a sweeping transportation bill passed this year and signed by McDonnell.

This story has been updated.