CHICAGO (CBS) — The Barack Obama Foundation has chosen a New York City architectural firm to lead the design of the Obama presidential library on the South Side, but a Chicago firm not among the initial seven finalists was also selected as a partner on the job.

The foundation announced it has selected Tod Williams Billie Tsien Architects, which designed the Logan Center for the Arts at the University of Chicago, to lead the design team for the library. Chicago-based Interactive Design Architects will partner with TWBTA on the project.

Interactive Design Architects, a minority-owned firm headed by South Side architect Dina Griffin, designed the Modern Wing at the Art Institute of Chicago.

Obama Foundation chairman Marty Nesbitt said President Barack Obama and first lady Michelle Obama made the decision.

“It was a really, really tough call to make; but it was based on this idea of chemistry and the ability to work together and collaborate that was key to the decision-making process, and nothing related to design,” he said.

President Obama once taught constitutional law at the University of Chicago, and the school also submitted the winning bid to host the Obama Presidential Library, which will be built in either Jackson Park or Washington Park. The foundation has yet to announce a specific site. Nesbitt said that decision will be made “substantially before” the end of the year.

No designs for the library have yet been released.

Tod Williams Billie Tsien Architects was chosen from among seven finalists for the job, but Interactive Design Architects was not on the list of finalists.

The other firms that submitted proposals for the library included Adjaye Associates of London, Diller Scofidio + Renfro of New York City, John Ronan Architects of Chicago, Renzo Piano Building Workshop, Genova, Italy, SHoP Architects in New York City, and Snøhetta in New York City.

Officials have said the library center could open as soon as 2020. It is expected to cost more than $500 million, funded by private donations to the Obama Foundation.