As Democratic leaders from Kamala Harris to Cory Booker to Elizabeth Warren line up behind Bernie Sanders’s proposal for a single-payer, “Medicare-for-all” health care system, there’s at least one person who is still not convinced: Hillary Clinton.

In an interview with Vox’s Ezra Klein, Clinton repeated attacks on single-payer she made during her primary campaign against Sanders, arguing that more modest measures like a public insurance option or a Medicare buy-in for people 55 and older are more realistic and achievable.

"I don't know what the particulars are" on Sanders's latest plan, Clinton said, but added, "He introduced a single-payer bill every year he was in Congress — and when somebody finally read it, he couldn’t explain it and couldn’t really tell people how much it was gonna cost."

She clarified that she'd support a bill opening up Medicare or Medicaid and cutting prescription drug costs, but cautioned, "I think it’s going to be challenging if within that bill, there are tax increases equivalent to what it would take to pay for single-payer, and if you’re really telling people — about half of the country — that they can no longer have the policies they have through their employer."

She noted that this issue arose in 1993-’94, when she was crafting a health reform plan in the Bill Clinton administration, and she concluded then that the forces arrayed against single-payer, not least of which were the public's fears about such a program, were insurmountable.

She also had a more recent example. “Look at what happened in Vermont,” she said, alluding to the failed effort to pass a single-payer plan in that state. “It wasn’t for lack of trying in Vermont. The Democratic political establishment was behind single-payer, and they worked for years to achieve it. This is in, you know, a small state, where it might’ve been possible. They were talking about an increase in the payroll tax of 9.5 percent, or I think, no, maybe 11.5 percent, they were talking about a sliding income scale, they went up to 9.5 percent — it just was so difficult to put pieces together.”

(Clinton’s higher estimate was right. The plan being considered would have involved an 11.5 percent increase in payroll taxes and a progressive income tax hike, with top earners paying 9.5 percent more.)

The in-one-leap approach of Vermont, Clinton argues, is doomed to failure, and a more gradual approach of building up public programs is preferable.

“You’re going to tell 50 percent of America, ‘You are no longer to have your employer-based health care, but oh, trust us, it’s going to be really good when we finally work out all the kinks’ — you’re going to have massive resistance by people, who are gonna say, ‘I’m happy with what I’ve got,’” she told Klein. “But if you say, ‘You know what, we need to lower the age for Medicare, and here’s how we can do that, and we need to continue the expansion of Medicaid,’ we will be at universal coverage. Then once we’re at universal coverage, and people know what that feels like, then we can begin to say, ‘Okay, here’s what we’re going to do to make it work better, to get the costs down.’”

Clinton is setting up an opposition that congressional Democrats are not

The set of approaches to expanding health coverage that Clinton alludes to are not exactly being ignored by Democrats in Congress and at the state level. Sen. Brian Schatz (D-HI) has a plan to let states open up Medicaid to anyone who wants to sign up, modeled off a bill that almost became law in Nevada that would’ve done the same.

Sen. Chris Murphy (D-CT) is working on legislation to open up Medicare to everyone, including employers, telling Vox’s Jeff Stein that “you’d naturally transition to a single-payer system without a massive political fight. … This may be the fastest way to a single-payer system.” This is the same intuition behind AmeriCare, former Rep. Pete Stark’s (D-CA) 2006-era universal health care plan, modeled on work by Yale political scientist Jacob Hacker and UC Berkeley economist Helen Halpin.

But while Clinton presents an aggressive public option–based transition as an alternative to the single-payer proposals of Sanders, a lot of Democrats in Congress don’t see things that way. Schatz is co-sponsoring Sanders’s Medicare-for-all bill. Sens. Cory Booker (NJ), Tammy Baldwin (WI), Sheldon Whitehouse (RI), Jeff Merkley (OR), and Richard Blumenthal (CT) have all co-sponsored a bill from Sen. Debbie Stabenow (MI) that would let people buy into Medicare at 55. But they’ve also stated their intention to co-sponsor the Sanders bill.

Where Clinton sees an and/or debate, in other words, many senators see a both/and.

That makes a certain degree of sense. All of these proposals — switching to Medicare-for-all overnight à la Sanders, transitioning with a buy-in à la Murphy, opening up Medicaid à la Schatz and Medicare à la Stabenow — move in the same broad direction, toward the government directly insuring more people and employers insuring fewer. Current senators are choosing not to be particular about what specific plan they choose, and instead are embracing an array of options.

Clinton’s counterargument is that some options are more viable than others, and some will get you killed politically — and she thinks overnight single-payer falls into that category.