Changing the tax treatment of employer-provided health insurance could provide one of the largest potential sources of financing for a new refundable credit. It also would bring hefty trade-offs. On the political side, capping the deductibility of employer-based health plans to finance refundable credits that are considered government spending would not please some Republicans. Put another way: Repealing Obamacare’s tax increases to replace them with other revenue increases is unlikely to go over well with conservative voters, as I wrote in Think Tank late in 2014.

On a more technical level, such tax changes pose a “Goldilocks” problem. Some believe that an Obamacare alternative could cap the deductibility of employer-based insurance in a way that would raise enough revenue to fund subsidies for most, if not all, of those newly covered by the law, while leaving employer-based coverage unchanged for the vast majority of plans and workers. Achieving one of these goals would be difficult; achieving both simultaneously could be impossible.

Financing a refundable tax credit through reforms to Medicaid would raise other concerns. Some noteworthy examples suggest that giving states additional flexibility over benefit parameters would flatten the growth of Medicaid spending. But the Congressional Budget Office might conclude that such changes would cause states to reduce the number of individuals covered by Medicaid. Liberal advocates of Obamacare’s coverage expansions are almost certain to argue this. And if achieving coverage gains is an objective of an Obamacare alternative, budget scorekeepers are likely to note that reforming Medicaid to finance a refundable tax credit could work at cross-purposes.

House Republicans could decide to use Medicare savings to finance a new refundable tax credit. That, however, could lead to charges of hypocrisy because of the political attacks Republicans have leveled against President Barack Obama for funding the 2010 health-care law this way and because of the optics of using one entitlement program to fund another. Likewise, Republicans could, in theory, propose a new refundable credit without any method of paying for it—but such a proposal may not receive enough support to ensure passage.

It’s also possible that House Republicans’ proposal may attempt to obscure the conflicts and trade-offs that come with crafting a health plan. Mr. Obama arguably did that as a presidential candidate in 2008, and it’s a major reason his health-care efforts enjoyed widespread popularity through early 2009. Once the messy trade-offs necessary to construct the law—the individual mandate, tax increases, and Medicare reductions—were clear, the effort’s approval ratings plummeted. They remain low today. Given what happened with Obamacare’s crafting and rollout, Republicans’ failure to acknowledge the policy trade-offs necessary to enact an alternative to that law could win a short-term political battle—but cost them a long-term policy war.

This post was originally published at the Wall Street Journal Think Tank blog.