CHICAGO (CBS) — The tax plan proposed by Republicans in Congress would eliminate the Historic Tax Credit Program, and some fear it will put some major projects in Chicago at risk.

Developers have been working to rehab the Old Main Post Office straddling Congress Parkway for a year and a half, but some fear the work could be threatened if a 20 percent tax credit for developers is taken away under the Republican tax plan.

The Lathrop Homes mixed-income housing project also might be threatened. Officials formally broke ground on the 1,100 new and rehabbed units there last month. The project includes historic preservation of 16 buildings.

Past projects that have benefited from the Historic Tax Credit program include the conversion of the Carson Pirie Scott building into a Target store at 1 S. State St.

Developers saved money rehabbing the Wrigley Building as well.

In all, at least 269 projects in Illinois cashed in on the tax credit over the past 14 years, saving more than $564 million on income taxes.

Those who want to eliminate the tax have argued in the past that it benefits already wealthy developers.

The program was launched in the 1970s under President Gerald Ford. Supporters argue it generates more in tax revenue than developers save, by creating jobs, and generating more business taxes, property taxes, and income taxes.