CHICAGO (AP) — Illinois officials have started negotiations with a development group to sell the James R. Thompson Center for $70 million up front, Gov. J.B. Pritzker said Wednesday.

Longtime developer Michael Reschke, who leads The Prime Group, will head development of the 17-story building that houses offices for Pritzker and other state leaders. The group plans to retain the design of the 17-story curved glass structure in downtown Chicago.

The state plans to keep some office space in the building. Some agencies have already moved to a building in the city’s West Loop.

Reschke expects the sale to close within six months and renovations to start within a year.

State officials have tried for years to sell the building, which is expensive to maintain and requires hundreds of millions of dollars in repairs.

The Thompson Center opened in 1985 and was designed by famed architect Helmut Jahn, who died in May.

State officials said the move allows Illinois to be more efficient and save taxpayers over $800 million.

“This strategic public-private partnership allows us to retain a smaller presence in the property while partnering with an established development team to transfer significant financial risk and responsibility for the much-needed capital improvements at the James R. Thompson Center to a third-party,” Janel Forde, director of the Department of Central Management Services, said in a statement.