WASHINGTON (AP) — Democratic presidential candidates campaigning on "Medicare for All" are wrestling with how to pay for the dramatic overhaul of the American health care system.

Bernie Sanders, the chief proponent, says "Medicare for All" could cost up to $40 trillion over a decade. He's been the most direct in discussing how he'd finance it, including higher taxes on the middle class — which he argues would ultimately cost less than the current health care system.

But his rivals who also support "Medicare for All" have offered relatively few firm details so far about how they'd pay for it beyond raising taxes on top earners.

As health care dominates the early days of the Democratic primary, some experts say candidates won't be able to duck the question for long.