Mayor Vincent C. Gray’s chief of staff resigned Tuesday moments before she was scheduled to testify before a D.C. Council committee on why some members of the administration were being paid above the legal limit.

Gerri Mason Hall, a former executive at Sodexo, will be replaced by Paul Quander on an interim basis.

Gray selected Hall in December to head up his office, but there have been growing calls for her resignation in recent days following a string of news reports about the administration’s rocky start.

Hall has been described as a protege of Lorraine Green, one of the mayor’s closest friends and advisors.

On Tuesday morning, Hall was scheduled to testify before the Committee of Government Operations and the Environment to explain why some top Gray staffers were given salaries above the legal limit. Hall sat in the hearing room much of the morning waiting to testify.

But Council member Mary M. Cheh, the chair of the committee, adjourned the hearing shortly before 2 p.m. and walked up to the mayor’s office.

Cheh returned about 30 minutes later and told reporters she was told Hall would not be testifying.

“I was expecting a very vigorous session with Ms. Hall,” Cheh said. “I was going to be very vigorous in both scope and types of questions I would ask.”

Shortly before 5 pm, Gray held a hastily scheduled news conference to announce Hall’s resignation.