A deal to build a baseball-soccer stadium in Loudoun County was announced Monday, significantly bolstering the prospects of a North American Soccer League expansion franchise in Northern Virginia for the 2014 season.

The facility will be part of One Loudoun, a planned development at the intersection of Route 7 and Loudoun County Parkway — nine miles north of Dulles International Airport and about 30 miles west of Washington. The stadium project calls for 5,500 permanent seats and space to accommodate about 10,000 spectators.

The NASL’s board of governors could ratify the franchise bid as early as Oct. 26-27, the league’s championship weekend.

“We have a few more steps to go, but it’s looking real good,” said Bob Farren, president and chief executive of VIP Sports & Entertainment, which would own and operate both the soccer club and a minor league baseball team in Ashburn. Farren met with NASL Commissioner David Downs in San Antonio last week. Farren has been in talks with the NASL for some time, but the lack of a firm stadium plan was a major hurdle.

Downs had not been briefed on the latest developments and didn’t want to comment at this time, an NASL spokesman said.

VIP negotiated for several years with another real estate developer, Kincora, about constructing a stadium about a mile away from One Loudoun. But the window of opportunity to secure league entry for the baseball and soccer teams was closing, Farren said, so his group entered talks with One Loudoun.

To accommodate two sports playing at the same time of year, artificial turf will cover the playing surface. Other details have not been finalized, but Farren envisioned a field conversion plan that would, at times, allow for staging baseball in the afternoon and soccer at night.

The NASL, named after the famed pro league of the 1970s and ’80s, fielded eight clubs this year: Atlanta, Carolina, Edmonton, Fort Lauderdale, Minnesota, Puerto Rico, San Antonio and Tampa Bay.

The New York Cosmos will begin play next year at Hofstra University on Long Island. Ottawa will join in 2014. NASL teams operate independently and are not formally affiliated with MLS, which has 19 clubs, larger budgets and bigger stadiums.

Both the New York and Washington markets have MLS clubs — the New Jersey-based Red Bulls and D.C. United. But the distance between the stadiums in the respective areas, the different caliber of the leagues and the hyper-local audience that NASL seeks in the distant suburbs shouldn’t cause much overlap.