THE NONPROFIT that administers the District’s program of federally funded school vouchers held two open houses to solicit interest from low-income families for the upcoming school year. The response was overwhelming; nearly 1,200 new applications were received. Most applicants are likely to end up disappointed because of a misguided decision by the Obama administration to effectively deny new students access to the successful program.

House Speaker John A. Boehner (R-Ohio) and Sen. Joseph I. Lieberman (I-Conn.) met last week with Education Secretary Arne Duncan to urge him to lift what they see as an artificial cap on the D.C. Opportunity Scholarship Program. The popular program, now in its eighth year, allows children from low-income families to attend private schools with federally funded vouchers of up to $12,000 annually. The cap of 1,615 students is well below the number of students previously accommodated by the program (1,903 in 2007-2008, for example) and has meant that new students aren’t being admitted. Not only does that close the door to better schools for students most in need, but it would also make it impossible for researchers to conduct the congressionally mandated evaluation of the program. Patrick Wolf, an investigator for the Institute for Education Sciences who has done past studies of the program, told congressional staff that a credible study could not be done without the addition of several hundred new students.

The administration insists that a cap is necessary because it’s unclear whether the program will be funded next year; funds must be held in reserve to ensure the continuation of scholarships for currently enrolled students. It’s a rich argument, since any uncertainty about funding is entirely due to administration actions. As Mr. Boehner wrote on a blog Tuesday, it was President Obama who “inexplicably” zeroed out funding for the program in his budget proposal, a decision in direct contradiction to a law he signed last year that authorized full funding for vouchers, along with monies for D.C. charter and traditional public schools. That legislation contains no cap on enrollment.

Mr. Boehner has made clear that Congress will provide the funds for this program, but because the group in charge of the program is now being forced to abide by the artificial cap, many students will unnecessarily be deprived of scholarships. In other words, when the money becomes available, it will be too late.

Now is the time that families are making decisions about schools for the fall. Unless Mr. Obama and Mr. Duncan are intent on denying hundreds of underprivileged D.C. students the chance for a quality education, they should work with Mr. Boehner to ensure the uninterrupted continuation of this important program.