CHICAGO (CBS) — A spat has erupted between Mayor Rahm Emanuel and the head of the National Restaurant Association over the dates of the annual event, which will overlap with the NATO and G8 Summit.

As WBBM Newsradio 780′s Mary Frances Bragiel reports, the National Restaurant Association show is set for May 19-22 at McCormick Place. The recently-announced NATO and G8 summit is set for May 15-22.

LISTEN: Newsradio 780′s Mary Frances Bragiel reports

Crain’s Chicago Business is quoting sources as saying Mayor Emanuel and Mary Pat Heftman, the head of the show had a contentious meeting recently as city officials want the dates for the restaurant show to be moved to an earlier timeframe in May.

The show generates more than $100 million for the Chicago economy, so Crain’s says some financial incentives were likely involved in the efforts in the request to move the show.

The NATO and G8 summit is expected to attract world leaders and tens of thousands of visitors, and was to be held at UIC. But officials say that site will not work, given that more than 10,000 visitors will be coming with their own security and needs for high-end hotel space, Crain’s reported.

Sources tell Crain’s Heftman went ahead and booked rooms in Las Vegas once she learned about the summit.

The Restaurant Association signed an agreement this past November to keep its trade show at McCormick Place through 2016.

“We continue to strongly believe that Chicago, Illinois, is a world-class destination that provides outstanding business facilities, along with sensational culinary, cultural and entertainment assets,” Restaurant Association president and chief executive officer Dawn Sweeney said in an news release at the time.

But that decision followed the passage of a state law that cut labor costs at McCormick Place after complaints by many exhibitors that union rules were making costs prohibitively high. A federal judge last month ruled against the new law, saying state lawmakers went beyond the terms of union contracts.