HERE’S HOW most reformist politicians try to operate: They find something that doesn’t work and offer possible solutions. Even if, as is often the case, their efforts come up short, there is at least some merit in trying to fix a problem.

D.C. Council member and mayoral hopeful David A. Catania (I-At Large) seems to embrace a different approach: Take something that is working reasonably well and offer proposals that threaten to undo that success. In the year since he assumed control of the council’s education committee, Mr. Catania has loosed a barrage of proposals that seek to substitute his judgment and priorities for those of school officials, endangering in the process important progress that’s been made in school improvement.

His latest brainstorm, a new program of college scholarships, threatens one of the District’s most successful initiatives, according to Del. Eleanor Holmes Norton (D-D.C.).

Ahead of Tuesday’s council vote on Mr. Catania’s D.C. Promise proposal, Ms. Norton sent a sharply worded letter to the council, detailing concerns that if a flush District government has the money to provide its own scholarships, Congress would withhold funding for the popular D.C. Tuition Assistance Grant (TAG) program. TAG offers subsidies to District students attending out-of-state public universities, universities in the Washington area or historically black colleges.

“I write now because if the current Promise bill passes, whether or not funded, the Council should be prepared to fund at least any current DCTAG students who may lose DCTAG funding and to fund future students, if necessary,” she wrote in a rare rebuke of local officials.

Mr. Catania, backed by D.C. Council Chairman Phil Mendelson (D), counter that the Promise scholarship is dissimilar from TAG and will supplement, not supplant, the federal program. Mr. Catania said he plans to offer further revisions to the proposal to deal with Ms. Norton’s concerns.

Making college more affordable, particularly for low-income students, is a laudable goal, but there are too many questions about Mr. Catania’s proposal. The D.C. Fiscal Policy Institute warns that the costly initiative would make it difficult to fund other pressing education priorities. The group also noted that most Promise programs around the country are privately funded, a route that should be explored for the District. The council should table this legislation and return to the drawing board for an approach that doesn’t risk a program that already — at federal expense — makes college more accessible and affordable for D.C. families.