For the first time in over a decade, Barack Obama is a Medicare for All supporter.

On September 7 in Illinois, Obama promoted the idea while campaigning for Democrats ahead of the 2018 midterm elections. “Democrats aren’t just running on good old ideas like a higher minimum wage,” he said, “they’re running on good new ideas like Medicare for All.” His is the biggest endorsement from the political center for the idea, and a sign that Democrats are beginning to yield to this overwhelmingly popular demand — a recent Reuters/Ipsos poll showed that 70 percent of Americans support the plan.

But Medicare for All supporters should be skeptical of Obama’s support. Centrists are engaged in an ongoing effort to reinterpret what M4A means, which could lead to a watered-down proposal that throws the possibility of achieving single-payer health care into jeopardy.