The Federal Transit Administration has committed $1.97 billion to extend the CTA Red Line south to 130th Street, a key source of funding that will allow the long-awaited project to move forward.

       The federal commitment is expected to cover half the cost of the extension. The CTA hasn’t received most of the money yet, but the funds are considered locked in for the agency as the project progresses into future phases.

       The money is less than the CTA initially sought for the extension of the Red Line, the transit agency’s busiest route. The agency had requested $2.37 billion, or 60% of the estimated project cost. It was an unusually large request, and the federal agency told the CTA the maximum it would pay was half the cost of the project. That leaves the CTA with some $400 million less than it had asked for.