Republican lawmakers in Augusta this week announced what they said is an alternative to an idea they don't like, the expansion of Maine's Medicaid program under the Affordable Care Act. Their plan would be to have the uninsured buy coverage on the online marketplace. About half of Mainers who would be covered under the expansion currently qualify for subsidies to purchase insurance on the marketplace for just a few bucks a month. But expansion proponents said that solution isn't as simple as it seems.