Michelle Rhee's vigorous 3 1/2 years as head of the Washington, D.C., public school system recently came to an end, in part because of the deep pockets of the American Federation of Teachers. But it is too soon to say who won the hard-fought battle for the control of District schools, the unions or the reformers.

A $1 million campaign contribution from the AFT helped Vincent Gray defeat incumbent Mayor Adrian Fenty, Ms. Rhee's ally, in the city's Democratic primary in mid-September. That all but assured Mr. Gray's election in the general election on Tuesday.

By then, Ms. Rhee had already resigned, saying it was "heartbreaking" to leave before her reforms have taken root. The capital's schools have perennially ranked among the worst performers in the nation.

But Ms. Rhee is a tough negotiator, and before her departure got Mr. Gray to promise that he will keep her management team in place under her deputy chancellor through the next school year. That means the next 12 months will be critical in determining the outcome of the test of wills between reformers and the teachers' union. A new teachers' contract negotiated last summer ties teacher bonuses to classroom performance, but the details of the performance system have yet to be ironed out.

The union has every incentive to try to gut the performance measures and may get support from Mr. Gray. However, a grant of $75 million from the federal Race to the Top educational reform program is tied to the city's commitment to continue Ms. Rhee's reforms.

So the room for backsliding is limited. Michelle Rhee is gone, but she and Washington's schoolchildren may still come out the winners in the epic battle to reform D.C.'s appalling public schools.