New York Democratic Senator and presidential aspirant Kirsten Gillibrand is calling herself a Medicare for All supporter, but seems to be redefining a single-payer system – where everyone automatically has Medicare regardless of ability to pay – with a voluntary public option, which would be far more expensive.

She told a crowd in Iowa that she’s been for Medicare for All since she represented a conservative upstate New York district. But she never sponsored the House single-payer bill and didn’t sponsor one in the Senate until 2017. A public option or Medicare buy-in is a very different policy than a single-payer system. The first is much more expensive for individual Americans, the second is much more expensive for the government.The difference between what is essentially the Canadian system (single-payer), and some Americans having access to a cheaper health insurance plan to buy is massive.

This blurring of the lines is probably how some Democrats will claim to be for Medicare for All while opposing single-payer. Some may even do this after having spent 2018 supporting key lawmakers who were opposed to single-payer health care.

Last year, Gillibrand endorsed incumbent Democratic governor Andrew Cuomo, a single-payer opponent, over his primary challenger Cynthia Nixon, a single-payer advocate. She also endorsed the daughter of a Blue Cross executive who campaigned against single-payer in Michigan, despite the fact her chief primary opponent Abdul El-Sayed was a progressive who proposed one of the most comprehensive state single-payer programs in the country. Independent Vermont Senator Bernie Sanders endorsed El-Sayed.

Kamala Harris, another recent convert to the Medicare for All cause, chose to endorse Dianne Feinstein, an opponent of Sanders’s bill, during California’s U.S. Senate race. Feinstein defeated single-payer proponent Kevin De Leon. Sanders did not endorse in this race.

In Ohio, Elizabeth Warren, who also failed to endorse single payer until 2017, endorsed Richard Cordray over single-payer proponent Dennis Kucinich in that state’s governor’s race. Sanders did not endorse in this race.

In the cases of all three Senators, it’s unlikely that they chose their endorsements with the intention of stymieing single-payer health care. If I had to guess, Harris endorsed Feinstein because they are Senate colleagues and she wanted her political support in her upcoming presidential bid (Feinstein prefers Biden anyway). Gillibrand endorsed Cuomo because she once worked for him, and probably wanted his support in her bid (he also prefers Biden). Warren endorsing Cordray, a former Consumer Financial Bureau Chief, isn’t super surprising. She was standing with a former ally in her marquee cause of financial regulation.

But these endorsements do demonstrate a big difference with Sanders. He has spent decades arguing for the merits of single-payer, and he spent 2018 campaigning for candidates who believed in it (although he sat out some races). The rest of the potential 2020 field did not, as they only recently endorsed the concept of Medicare for All, which to them may simply end up being a public option you buy into. Sanders clearly prioritized single-payer, while the rest of the field seems to be courting it rhetorically but not making the political moves necessary to enact it.