Facing a Thursday deadline for passage, the state Senate leadership has refused to detail its Medicaid expansion plan, leaving members in the dark and health experts worried the plan could ultimately include elements that are unfeasible, costly and counterproductive. Two-and-a-half months into the legislative session, and after 10 years of debate, Senate Medicaid Chairman Kevin Blackwell told Mississippi Today on Monday afternoon that there was no update on a Senate proposal to expand Medicaid eligibility to the working poor and said, “we’re still working on it.”Two weeks after the House overwhelmingly passed a bill to expand Medicaid, the Senate has not brought the House measure up, even in committee, and Senate leaders refuse to comment on it.