DOVER — Delaware’s director of the Office of Management and Budget will leave next month after serving more than seven years in the administration of Gov. Jack Markell.

Ann Visalli, who has worked with Gov. Markell for 17 years and previously served as his deputy state treasurer, will become the newly established chief operating officer of St. Andrew’s School in Middletown.

The governor also said he will nominate the deputy director of the office, Brian Maxwell, to lead the agency.

Ms. Visalli was the governor’s first cabinet appointment in January 2009.

“I cannot thank Ann enough for her service to the citizens of Delaware and her leadership of OMB, especially during

Ann Visalli

such challenging times for our state’s budget,” Gov. Markell said in a statement issued Friday.

“Ann has never been afraid of a challenge and she certainly has overcome many since the start of my Administration, finding savings for taxpayers while maintaining key services, and ensuring we have invested in the areas like education and workforce training that are vital to our success in the new economy.”

He said she would be “a great addition to the St. Andrew’s School, taking on a new role that is a natural extension of her career in public service.”

St. Andrew’s was founded in 1929 by A. Felix duPont. The private school has an enrollment of 310, according to its website.

Ms. Visalli began her career in government at the Department of Services for Children, Youth and their Families and in the Controller General’s Office in the General Assembly.

She has served in leadership positions including for the Council of State Governments and the National Association of State Budget Officers.

She holds bachelor’s and master’s degrees in economics from the University of Delaware,

“It has been a privilege to serve the people of Delaware for as long as I have,” Ms. Visalli said. “I feel so fortunate and grateful to have had the opportunity to be OMB director and that the governor has had such confidence in me.

“It has been a team effort since day one. Any success I have had as OMB director is a direct result of the support I receive from the governor, the cabinet and my OMB family.”

She was selected for the St. Andrew’s position after a national search process.

“Ann, in the role of COO, will work closely with the Board of Trustees and me to inspire strategic thinking and planning and financial sustainability,” said Headmaster Daniel T. Roach, Jr.

The state senate will consider the nomination of Mr. Maxwell to succeed Ms. Visalli when the General Assembly returns to session.

Prior to becoming deputy director, Mr. Maxwell served as the office’s director of Budget Development and Administration and as Cash and Debt manager for the treasurer’s office from 2005 to 2009.

He previously worked as an assistant vice president at Citigroup Inc., managing parts of the company’s global loans initiatives.

The governor said Mr. Maxwell is “an ideal leader to build on the work” at the Budget Office because he has “a deep understanding of the state’s finances.”