The city, which owns the convention center, is working on a plan to expand or replace Cobo and is looking to Wayne, Oakland and Macomb counties to help finance that expansion. Patterson had complained that the city was not providing the financial records needed to determine whether his county would participate in paying for an expanded convention center. He broke off talks on the expansion in August. A task force has proposed that a regional authority own and run the center, financed by a 30-year extension of regional hospitality taxes set to expire in 2015.

"We feel an outside and independent agency is necessary at this time in order to help us resolve the breakdown in obtaining critical financial data regarding the Cobo Hall project," Patterson says.

Cobo has 2.4 million sf of space, but the largest exhibition area is only 700,000 sf. Last expanded in 1989, the facility has been criticized as too small for Detroit's biggest annual event, the North American International Auto Show.