LAS VEGAS (AP) — Rank-and-file Democrats appear to be shifting to the middle on health care, worried about what’s politically achievable on their party’s top 2020 issue.

While “Medicare for All” remains hugely popular, the majority say they’d prefer building on “Obamacare” to expand coverage instead of a new government program that replaces America’s mix of private and public insurance.

Highlighted by a recent national poll, the shifting views are echoed in interviews with voters and the evolving positions of Democratic presidential candidates. Some have backed away from the government-run plan championed by Sens. Bernie Sanders of Vermont and Elizabeth Warren of Massachusetts that for months had seemed to be gaining momentum.

It could mean trouble for Sanders and his supporters, signaling a limit to how far Democratic voters are willing to move to the left amid doubts that Americans would back such dramatic changes to their health care.

“We hear Medicare for All, but I’m not absolutely certain what that means and what that would then mean for me,” said Democrat Terrie Dietrich, who lives near Las Vegas. “Does it mean that private insurance is gone forever?”

She thinks it’s important that everyone has health care, not just those who can afford it. She said she would support Medicare for All if it was the only way to achieve that.

But “I don’t think we can ever get it passed,” Dietrich added.