Forty-second Ward alderman Brendan Reilly says he didn't get very far when he sat down with officials from the Chicago Children's Museum earlier this week to talk about potential sites for their new facility. They're only interested in one: Grant Park.

"They've refused to consider any other locations, and they've defined their parameters so narrowly that it will be practically impossible to find a place for them anywhere but Grant Park," he says.

Reilly opposes the museum's plan to build a new facility in the park because he believes it would violate a century-old city commitment to keeping the space clear and open to the public. Last month he wrote museum CEO Peter England and board president Gigi Pritzker-Pucker a letter asking them to consider other sites proposed by people from across Chicago, including downtown locations like Northerly Island, the old post office, the Riverwalk, and the South Loop. "I am writing to ask the Museum to review this list of suggested alternative locations and provide me with your evaluation of these potential sites," he wrote.

The alderman says the alternatives were rejected out of hand. "They didn't really offer specifics," he says. "They just said, 'No, those aren't suitable.'"

Spokeswoman Natalie Kreiger says the museum took the time to look into alternatives months ago. "Before we even focused on Grant Park, we did our due diligence and looked at a number of sites, and we found that Grant Park was the only one that met our criteria," she says. Those specifications include a central location, access to public transportation, and room for parking.

The museum doesn't see any reason to compromise. "We're going to pursue this site," Kreiger says. She adds that it's "fair to say" the museum is prepared for a political or legal showdown.

Reilly says he's been spending a couple of hours each day trying to build and retain support among other aldermen, who would have to defy the mayor to back Reilly. Meanwhile, the museum just hired a big public relations firm to help drum up support and has been busy doing its own lobbying in the City Council. "We have a lot of people and consultants working for us in a wide variety of ways," Kreiger says.