Republican Pennsylvania Gov. Tom Corbett announced Monday that he would agree to expand Medicaid under Obamacare, adding his state to the short but growing list of GOP-controlled states that have signed onto one of the law's key provisions. Corbett's acceptance comes with a few caveats. He wants to use Medicaid money to purchase private health coverage for low-income people on the law's health insurance marketplaces rather than enroll them in traditional Medicaid, a concept first introduced by Arkansas earlier this year.