WASHINGTON (AP) -- After two years of political battles and a Supreme Court case, many if not most states are expected to tell the federal government Friday if they're willing carry out a key part of President Barack Obama's health care overhaul.

At issue is the creation of new health insurance markets, where millions of middle-class households and small businesses will shop for private coverage. The so-called exchanges will open for business Jan. 1, 2014, and most of their customers will be eligible for government subsidies to help pay premiums. The exchanges will also steer low-income people into expanded Medicaid programs, if states choose to broaden their safety net coverage.