Mayor Vincent C. Gray announced Friday he’s replaced Harold Pettigrew as the director of the Department of Small and Local Business Development amid concerns that he was not moving aggressively enough to reform programs under his control.

Gray (D) said in statement that Pettigrew was being replaced by Robert Summers, the agency’s chief of staff. The change is effective immediately, and reflects Gray’s frustration about the pace of progress within city’s Certified Business Enterprise program, according to officials familiar with the matter.

“Mayor Vincent C. Gray, City Administrator Allen Lew and I think Harold for his service and wish him well in the future,” said Victor L. Hoskins, the deputy mayor Planning and Economic Development, said in a statement. “The Gray administration will continue to move forward aggressively with the reforms needed in our local Certified Business Enterprise program.”

In an e-mail to friends and associates, Pettigrew said he was “proud” of his service at the agency. “It has been an honor to lead DSLBD through the most aggressive expansion of small business services offered by the District, which have increased the competitiveness of, and opportunities available for, DC small businesses,” Pettigrew said. “During my tenure, DSLBD has launched programs and services for small businesses across various industries, and have established new opportunities in the local, regional, federal and global marketplace. “

Gray spokesman Pedro Ribeiro would not elaborate, calling it a personnel matter.

But Pettigrew has been on rocky footing with other senior Gray administration officials for several months.

Last month, he was admonished after he sent a tweet allegedly aimed at D.C. Council member Vincent B. Orange (D-At Large), the chairman of the Committee on Business, Consumer and Regulatory Affairs, during an oversight hearing.

According to the Washington City Paper, which reported on the matter last month, the now-deleted tweet referred Orange’s leadership skills.

Orange questioned Pettigrew about the matter, but said Friday he did not push for his dismissal.

After the tweet was sent, Orange said Gray informed him he would address the matter. Pettigrew and Hoskins also called him to apologize.

“I view this as an opportunity to move forward with CBE reform,” Orange said. “I agree that the CBE needs new leadership and certainly needs leadership that is going to be open to ideas that will benefit the CBE community.”