More Democrats seem to be having doubts about the federal health care law, a contentious issue for most of President Barack Obama’s tenure and one of the defining elements of his legacy.

With the administration counting down its final year, Sen. Bernie Sanders’ call for “Medicare for all” appears to have rekindled aspirations for more ambitious changes beyond “Obamacare.”

That poses a challenge for Hillary Clinton, who has argued that the health care law is working and the nation should build on it, not start over.

. . .