Shortly after announcing her presidential campaign in January, Sen. Kamala Harris said she’d get rid of private insurance as part of her plan to enact a “Medicare for all” single-payer health care system. That didn’t go over so well with the 177 million Americans who have private coverage and would lose it. So Harris backtracked from that and promoted a Medicare for all plan that would include private insurers. Confusion ensued.

Harris dropped her presidential bid on Dec. 3, as she sank in the polls and funding dried up. Her shifts on health care didn’t single-handedly sink her campaign. But it mystified voters and typified the difficulty Democratic candidates are having pushing for health care reforms that are both transformative and doable.

With Harris gone, the main Democratic candidates who support Medicare for all are Bernie Sanders—who wrote the damn bill—and Elizabeth Warren. Sanders’ socialist preferences are well known, and his support among Democrats has consistently run around 20% for most of the current campaign. Warren is newer to voters, and she’s been developing fresh policy proposals for the last several months. And like Harris, Warren has vacillated on health care as voters seem to disapprove.

Warren hit a high point in October, when a Quinnipiac poll showed her in first place nationally, with 28% of Democratic voters saying Warren was their first choice for president. Joe Biden was second, with 21%.

At the same time, however, Biden and many others were pressing Warren to explain how she’d pay for Medicare for all, which would probably require a doubling of federal outlays each year and sharp tax hikes to finance it. Sanders has suggested he’d pay for the giant plan with a 4% income-tax surcharge on families making more than $29,000. Families would still end up better off, he says, since they’d pay nothing for health care.

Warren won’t commit to a middle-class tax hike because she knows her opponents would pound her for it if she did. So in early November she released a plan to finance Medicare for all with a wealth tax on millionaires, new business taxes, reduced military spending and better efficiencies. The middle class would get something—free health care—for nothing, as long as her lowball cost estimate for Medicare for all and highball revenue estimate for new taxes panned out.

In case they don’t, Warren now has a backup plan. In mid-November, Warren released a “transition” plan that would come before Medicare for all. This would be a new public health plan for people who need it that leaves private insurance in place. It’s very much like the “public option” plans Pete Buttigieg and Joe Biden support. Both of those campaigns trashed Warren for flip-flopping and trying to kill private insurance in the first place.