According to the Kaiser Family Foundation’s latest Health Care Tracking poll, a small majority of adults still say they would favor putting all Americans on a single national health plan, with 51 percent in favor and 47 percent opposed. But the margin of support has shrunk significantly from the beginning of this year, when as many as 57 percent backed such a proposal, and only 37 percent were opposed.

Recent polling by other organizations has shown even lower levels of support for a single-payer system. An NBC/Wall Street Journal survey last month found just 41 percent said they backed one, with 56 percent against, while a Fox News poll found 46 percent in favor and 48 percent against. But polling results on health care can be extremely sensitive to how the question is phrased. What makes the Kaiser Family Foundation survey interesting is that it’s been asking the public the same version of its question for more than two years now—“Do you favor or oppose having a national health plan, sometimes called Medicare-for-all, in which all Americans would get their insurance from a single government plan?”—giving us a picture of how public opinion has evolved. And it suggests that as single payer has become a more contentious political topic during the presidential campaign, it has lost a bit of its shine.