The D.C. Council will vote Tuesday on whether to override a rare veto from Mayor Vincent Gray.

Earlier this month, Gray moved to kill a package of reforms to the city's certified business enterprise program, citing the measure as "unworkable" and "short of the mark."

But at-large Councilman Vincent Orange, the proposal's author, told his colleagues in a Thursday letter that he "cannot understand why this bill was vetoed."

"The law we enacted put some real teeth in accountability for the CBE program through tougher sanctions against companies who misuse the CBE program as a means of gaining unfair advantage in the competitive contracting process when CBE utilization is required, which was the main emphasis for the reform bill," Orange wrote. "The council-passed legislation puts into law a CBE reform program that rewards good business practices, strengthens D.C. small and local business economic development policy, and works to the benefit of D.C. residents."

The 28-page bill includes an array of changes to the CBE program, including a requirement that 50 percent of the value of major contracts go to certified businesses, up from 35 percent.

The bill would also increase the number of available preference points. Under the proposal, companies could receive additional points for actions like hiring residents from areas with high unemployment and giving preference to ex-inmates.

A vote is scheduled for Tuesday. Two-thirds of the voting members must support an override for it to take effect. When lawmakers considered the measure last year, they approved it unanimously.