The former president of the agency overseeing development at the World Trade Center site has returned as its chairman.

Kevin Rampe, president of the Lower Manhattan Development Corporation from 2002 to 2004, replaces retiring John Whitehead as chairman of its board of directors, Governor Pataki said yesterday. His first task will be to make changes to the trade center memorial design that cuts its $1 billion budget in half and ensures it can be built in three years.

Mr. Pataki and Mayor Bloomberg appointed a leading city builder to help reconcile varying budget figures and design issues with the memorial and said a revised design would be ready by the end of June. Preliminary construction on the memorial began in March and is nearly complete.

The builder, Frank Sciame, has a firm that has restored the oldest synagogue in Manhattan, expanded Madame Tussaud’s Wax Museum and developed megastores for Virgin Records America Incorporated and Toys “R” Us Incorporated

Mr. Sciame, memorial architects Michael Arad and Peter Walker and trade center architect Daniel Libeskind, who drew the master plan for the 16-acre site, will come up with design changes to the memorial by June 15. The LMDC will then seek public comment on the changes and vote on them in July.

Mr. Rampe helped lead the design competition for the memorial and for the master plan for the lower Manhattan site. He had worked at the state Insurance Department, has been at the ACE Limited insurance firm since leaving the LMDC and is on the board of the World Trade Center Memorial Foundation, which is raising money to build the memorial.

“I think everyone was surprised” by the spiraling costs for the memorial, Mr. Rampe said yesterday.

But he said he was confident the design could be brought within budget while retaining the vision of Mr. Arad, whose “Reflecting Absence” design centers around two reflecting pools shaped like the fallen towers.

“I think it’s important that we’re going to move forward,” Mr. Rampe said.

Assembly Speaker Sheldon Silver scheduled a hearing today to address the rebuilding delays at the site.

Mr. Rampe said critics can miss the point that “we’re rebuilding, really, a city here.”

“Delays are inevitable,” he said.

The chairman, whose position is unpaid, heads the board and votes on resolutions at monthly meetings, while the president, who is paid, heads the staff and its day-to-day operations.

Mr. Rampe, who takes over immediately, “brings the dedication, experience, energy and insight necessary to keep the momentum going on the reconstruction of the World Trade Center and the revitalization of downtown,” Mr. Pataki said.