A Loudoun County Planning Commission public hearing Tuesday will focus on a controversial application to build a baseball stadium at the One Loudoun development in Ashburn, and both supporters and opponents of the stadium are intent on making their voices heard.

Dozens of opponents of the stadium are planning to attend the meeting, according to members of a group calling itself No Stadium on Route 7, which includes residents of neighborhoods adjacent to the One Loudoun development. As of Friday, 10 speakers from the Potomac Green community had signed up to voice their opposition to the stadium at the hearing, the group said.

Jean Beres, one of the group’s organizers, said a petition opposing the stadium had more than 280 signatures.

But the Loudoun Hounds, the Atlantic League baseball team that would play in the stadium, also put out a call to summon supporters and announced on the team’s Web site plans for a rally outside the Loudoun County Government Center before the 6 p.m. hearing.

The stadium, which would also be home to the Virginia Cavalry, a professional soccer team, was originally approved in 2009 by the Board of Supervisors as part of the Kincora mixed-use development at Routes 7 and 28 in Ashburn.

At the time, the Hounds’ owners, VIP Sports and Entertainment, hoped to open the ballpark in time for the 2012 season. That date was pushed back repeatedly, as Kincora’s developers struggled to secure funding for promised road improvements. In October, VIP announced that the stadium would move to One Loudoun, about a mile west, on Route 7.

Many residents of nearby neighborhoods, including the Potomac Green and Ashbrook communities, were unhappy about the change of plans. More than 130 people gathered at the Potomac Green community center in late November to discuss a strategy to stop the stadium’ from being built, citing concerns about traffic and noise and light pollution.

The stadium, which is to have 5,500 permanent seats but can accommodate nearly twice as many spectators, will host concerts, community events and festivals in addition to the baseball and soccer games, VIP officials said.

Shortly after the October announcement, Loudoun Board of Supervisors Chairman Scott K. York (R-At Large) and Supervisor Shawn Williams (R-Broad Run) recommended that the board initiate an amendment to the county’s Comprehensive Plan, which is needed to allow for the development of the stadium. They also recommended that all legislative and administrative plan submissions related to the development be expedited, as part of the county’s “Fast Track” program for high-priority projects.

VIP officials have expressed confidence that the process can be completed in time for the stadium to open for the 2014 season.

But a county staff report on VIP’s applications, which will be addressed at the Planning Commission meeting, raises red flags and recommends further discussion before action is taken.

Among those issues, the report says, are “inadequate design commitments” for the stadium; outstanding issues related to lighting, noise, event limits and surface parking on Route 7 and the surrounding area; questions regarding stadium capacity; and a lack of transit facilities capable of accommodating stadium-level events. County staff members also indicated concerns about some of the proposed zoning modification requests included in the application, such as the elimination of spacing requirements between buildings, the construction of an interim surface parking lot for the stadium and the removal of buffers and screening along Route 7.

Bill May, vice president of Miller & Smith, the co-developer of One Loudoun, said that additional information had been provided to county officials since the report was issued.

“We appreciate staff’s concerns, and we appreciate the adjacent communities’ concerns, and we’ve gone a long way to address those,” May said. “We’ve had further discussions with staff . . . and we expect that to come to light at the public hearing Tuesday night.”

May said the primary issues — traffic, light pollution and noise — were being taken seriously and will be resolved through thorough studies and plan revisions.

“I’m optimistic that we will be successful in getting this application approved. But I know that there are people who have legitimate concerns, and we’re going to address them,” he said.

May predicted that the stadium will generate less traffic than the 320,000 square feet of office space originally planned in its place. Morning rush hour traffic would no longer be an issue, he said, and people would be more likely to carpool for a game or community event.

Despite such assurances, opponents of the stadium seized on the county staff report as evidence that the stadium’s relocation is inherently problematic. A summary of the report’s findings was posted on the No Stadium on Route 7 Web site, along with an appeal for members of the affected communities to sign up to speak to the Planning Commission Tuesday.

They won’t be alone in the county boardroom.

“Mark our words, we need you,” the Loudoun Hounds Web site said. “This is a tremendously important item to be marked off the checklist before we can get rolling and actually build the [stadium] . . . time to put on your rally caps, Hounds Nation, and make your voice heard.”

The Planning Commission meeting will begin at 6 p.m. Tuesday in the Loudoun County Government Center in Leesburg. Residents may sign up to speak in advance by contacting the Planning Department at 703-777-0246 before noon Tuesday.

A rally hosted by the Loudoun Hounds is scheduled for 4:45 p.m. outside the government center.