A team rendering of the proposed new D.C. United stadium. (Courtesy of HKS)

Mayor Vincent C. Gray and his top deputies joined with D.C. United executives and real-estate developers to announce a tentative $300 million deal allowing the team to build a 20,000-seat soccer stadium at Buzzard Point in Southwest.

Emphasis on the “tentative.”

The deal is predicated on public property surpluses, land swaps, street and alley closings, tax abatements and other legal maneuverings that will require the approval of at least seven of the D.C. Council’s 13 members.

There’s a lot about the proposed deal that should make it relatively palatable: The team’s owners are ready to put up $150 million to build the actual stadium, the site is located in a fallow industrial district, and the team enjoys a devoted fan base and a good reputation among city officials. But it’s highly unlikely lawmakers will grant the imprimatur for the city’s matching investment without a good deal of hand-wringing and debate.

Herewith, some of the most likely complications:

The mayoral race. Three council members have announced they’ll run for mayor in next April’s Democratic primary, and a fourth is seriously entertaining mounting an independent run later in the year. Two of the Democrats, Jack Evans (Ward 2) and Tommy Wells (Ward 6), are already on the record supporting a soccer stadium at Buzzard Point. There’s reason to believe that the others, Muriel Bowser (D-Ward 4) and David A. Catania (I-At Large), might see the stadium deal as a way to draw a populist contrast with the other candidates — including, potentially, Gray. Bowser’s political mentor, former mayor Adrian M. Fenty, rode to the mayoralty in part on his opposition as council member to the Nationals stadium deal. Catania was from the beginning the most outspoken opponent of the ballpark financing scheme; to this day, he boasts about never having set foot in Nationals Park.

The money. As with the Nationals Park deal, the sheer amount of financing necessary is rhetorical fodder for opponents of the deal. “How can the city consider spending $150 million on a soccer stadium when the city has such dire need for affordable housing?” Or education. Or police officers. Or street paving. You name a priority; some council member will be speechifying about it. The effectiveness of the natural counter to those arguments — that the stadium is an investment intended to generate future revenue that can be spent on all those priorities — will depend on a detailed financial analysis that will be done ahead of a council vote by the Office of the Chief Financial Officer.

The property. Because the city is hard up against its statutory debt cap, limiting borrowing costs to 12 percent of yearly operating expenditures, City Administrator Allen Y. Lew had to get creative to pull this deal together. To secure one key Buzzard Point parcel belonging to development firm Akridge, the city has laid the 28-year-old Frank D. Reeves Center of Municipal Affairs on the bargaining table. That is a building with symbolic heft — more on that in a moment — and, crucially, one that carries former mayor and current council member Marion Barry’s name on the side. Will Barry (D-Ward 8) assent to the sale and likely destruction of one of the great concrete legacies of his mayoralty? As Lew hinted in an interview before the announcement, it’s no accident that the city is proposing locating the Reeves-tenant agencies to a sparking new complex in Barry’s Ward 8. Besides the Reeves center, the District will also have to come to terms with two other landowners: Pepco and office-security mogul Mark D. Ein. Other city properties are sure to be offered to both.

The numbers. Whatever numbers are presented at today’s news conference, one thing is certain: They will change. The city’s commitment to Nationals Park grew from $535 million to $611 million to nearly $700 million by the time all the bills were tallied — due largely to underestimated land acquisition costs. The soccer stadium deal is much simpler, but all three land owners — Akridge, Ein and Pepco — are savvy players who will be intent on getting top dollar for their land. How much will the costs inch up over time, fueling opposition to the deal? Will the team guarantee any overruns? Another potential cost driver to keep an eye on: Will council members demand the deal generate community benefits in their particular wards — recreation facilities, soccer camps, job training, etc. — in order to win their support? It happened with Nationals Park; don’t be surprised if it happens here.

The optics. What could more vividly illustrate a rapidly changing Washington than tearing down the Reeves Center, the city government’s pillar on Black Broadway, and using the proceeds to build a stadium purpose-built for soccer, a sport whose fans are overwhelmingly white and Hispanic? Quibble with that formulation if you want, but expect currents of race and class to flow underneath the soccer stadium debate. It doesn’t help that Akridge’s plans for the Reeves Center are likely to include luxury apartments and upscale nightlife, while city workers will be relocated to a somewhat less vibrant part of town. Much will depend on whether Gray and his allies can successfully sell the Reeves relocation as an attempt to recreate the U Street revitalization in Historic Anacostia. Barry went whole-hog in support of a soccer stadium when the plan was to build it on Ward 8’s Poplar Point. Having him on board for the Buzzard Point plan would ease matters tremendously.