Chicago leaders are searching for a company to build the city’s first casino, but big gambling operators are concerned that the government’s plans will be too costly to make the project feasible.

The city is calling for a megaresort with hotel rooms, meeting space and a surrounding entertainment district, according to a request for proposals issued in April. Chicago is hoping a casino will aid its underfunded pensions, said city officials.

Chicago’s requirements for the megacasino mean a developer could have to spend $1 billion or more to accomplish the task, according to one person familiar with the plans. Casino-resorts that have opened in Las Vegas and Boston in recent years, albeit on a larger scale than what Chicago has proposed, have cost $4.3 billion and $2.6 billion.