The D.C. Council and Mayor Vincent Gray are poised for a rare showdown Tuesday as lawmakers consider whether to override Gray's veto of a proposal to reform the city's certified business enterprise program.

"I cannot understand why this bill was vetoed," at-large Councilman Vincent Orange, the measure's author, said in a letter to his legislative colleagues last week. "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 CBE program, created in the 1970s, is designed to help direct contracts from the city government to businesses in the District.

But the program has been the subject of criticism amid allegations of pervasive fraud, and Gray and lawmakers called for reforms.

The 28-page bill that drew Gray's veto calls for an array of changes to the controversial CBE program, including a requirement that would increase the minimum amount of participation from certified subcontractors for certain projects.

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.

The D.C. Council unanimously approved the bill in December, but Gray has repeatedly decried it as "unworkable" and possessing "fatal flaws."

Business interests in the city have also sought to torpedo the proposal.

"The current proposal is ill-conceived and needlessly complicates an already convoluted system," said Barbara Lang, president and CEO of the D.C. Chamber of Commerce. "Mayor Gray showed strong leadership in vetoing this flawed legislation, and the business community is urging the council to support that veto."

During his 26-month tenure as mayor, Gray has made limited use of his authority to kill legislation: His decision to block Orange's bill was only the second time he issued a veto.

But on Monday, Gray said he couldn't remain passive or silent.

"I had to make a statement in this instance," Gray said. "This is not going to get us where we were trying to get to."

Orange, however, has blasted Gray.

"The mayor has caved to non-District based business interests," he said after Gray's initial veto decision. "This bill is pro-District of Columbia and for District-based businesses."