Polls suggest that the public considers health care the most important issue in the midterm elections. This immediately raises the question: Do voters understand what’s at stake? In particular, do they realize that if Republicans hold Congress, they will strip away protections for the 52 million Americans — more than a quarter of nonelderly adults — who have pre-existing conditions that, before passage of the Affordable Care Act, could have led insurers to deny them coverage?

In fact, the Trump administration is already trying to take away those protections via the courts. It probably won’t succeed. But it might, in which case an estimated 17 million Americans would lose their health coverage.

And even if the lawsuit fails, the administration’s support for an incredibly flimsy legal challenge — one so indefensible that three career Justice Department lawyers withdrew from the case — is a clear signal of Republican priorities: G.O.P. to Americans with health problems: Drop dead.

By the way, some people seem surprised by the administration’s moves here, since Donald Trump has promised many times to protect people with pre-existing conditions. But remember: The campaign against the Affordable Care Act has been based on lies every step of the way.