Somerville officials have named a Chicago development team to take the lead in building up to 2.3 million square feet of new commercial and residential projects in Union Square.

The redevelopment authority Thursday selected US2, a partnership between Magellan Development Group and Mesirow Financial of Chicago, as master developer for the project, which would cover 15 acres on Prospect Street, Somerville Avenue, Washington Street and Bow Street. The master developer would acquire the parcels through private negotiations or, if they failed, an eminent domain taking by the city.

Somerville hopes to capitalize on the anticipated stimulus effect of the MBTA Green Line Extension, with a new station in Union Square, to attract major corporate tenants to fill planned office and lab buildings and create 4,300 new jobs in the neighborhood.

Nine companies submitted presentations to a citizen advisory committee this spring. US2 was one of four finalists. The company has experience with major urban redevelopment projects, including the 28-acre, $4-billion Lakeshore East mixed-use development in Chicago.

US2 representatives said they want to retain the neighborhood’s existing character while enhancing public art and innovation space. They also emphasized their experience with historic properties and affordable housing.

In evaluations, members of a citizen advisory committee gave US2 credit for its diversity of architectural teams and extensive community outreach, but wondered if the Somerville project would be a big enough priority given the size of their other projects.

The other finalists were the Abbey Group of Boston, Gerding Edlen of Portland, Ore., and a partnership between Newton-based National Development and Federal Realty Investment Trust of Rockville, Md.