Arlington and Fairfax counties will not receive the $75 million in federal funding they need to build the Columbia Pike streetcar project, officials said Friday.

The announcement leaves much of the $249 million project in jeopardy. Officials will likely have to delay its opening if they can't find additional funding in their budgets or from the state.

Arlington County Board Chairman Walter Tejada said he has not received an explanation from the Federal Transit Administration about why the project was rejected.

"We will continue to explore all financing options, including federal financing," Tejada said. "While we are disappointed at not being included this year, we believe our application was strong, and will continue to work with FTA for [funding]."

Officials had hoped to receive $75 million in federal funding for the construction of the line, to be combined with $35 million in state funding and $140 million from Fairfax and Arlington counties.

The 5-mile line had been slated to run from Pentagon City to the Skyline area of Fairfax, but because only three of the streetcar's 19 stops are in Fairfax, Arlington officials agreed to pay 80 percent of the local cost.

Both counties have reaffirmed their commitment to constructing the line, however, and have vowed to find additional funding, possibly by reapplying to the FTA's Small Starts program.

"The Columbia Pike Streetcar Project is vitally important to the economic revitalization of Columbia Pike and the Skyline/Bailey's Crossroads area of Fairfax County," said Fairfax County Supervisor Penny Gross, D-Mason. "I am confident that the strong community and business support for the project and the long collaborative partnership between Fairfax and Arlington counties will merit federal funding in the future."