In a striking vote at its annual meeting this week, the American Medical Association’s policymaking arm nearly voted to overturn the physician group’s longstanding opposition to single-payer health care.

The House of Delegates, which sets the policy priorities and positions for the nation’s best-known medical association, voted on a resolution to reverse the organization’s opposition to single-payer. The vote failed, but narrowly: 47 percent voted to eliminate opposition to single-payer as an official policy position of the AMA, while 53 percent voted to maintain it.

We shouldn’t overinterpret one procedural vote at a professional conference, of course. But the vote does signal two important trends for the Medicare-for-all debate:

Single-payer continues to gain real momentum, even within the industry that would be significantly overhauled under such a system. Medical industry opposition might not be as monolithic as it first appears.

The AMA has been a powerful voice against single-payer health care for decades. In the 1950s, the organization helped mobilize against a push for national health insurance, preferring private employer-based coverage. It did support the Affordable Care Act but has more recently joined the Partnership for America’s Health Care Future, a conglomeration of hospitals, drugmakers, and other industry groups that is singularly focused on opposing the new energy around Medicare-for-all.

Bob Doherty, a senior vice president for government affairs and public policy at the American College of Physicians, tweeted after the vote that such a strong showing within the AMA for single-payer “would have been unimaginable in years past.”

Bottom-line: there is a large segment of the House of Delegates who support single payer (or don’t want AMA to oppose them) or public option approaches, as well as AMA’s new policies to close coverage gaps in the #ACA. This would have been unimaginable in years past. #AMAmtg — Bob Doherty (@BobDohertyACP) June 11, 2019

I asked Doherty what is changing within the AMA that might explain the surprisingly strong support for single-payer in this week’s vote. The group’s composition, for one, he said.

“The AMA House of Delegates has become younger and more diverse (especially many more women) over the years, reflecting the trend in who is going into medicine,” he told me. He also pointed out the rise of specialty medical societies, which tend to be more progressive, in the AMA ranks — which has undermined the long-held dominance of more conservative state medical associations.

“I also think physicians are frustrated with paperwork, preauthorizations, limited formularies, high-deductible plans, and narrow networks associated with private insurers,” Doherty added, “each with their own and conflicting rules.”

The AMA doesn’t speak for all US doctors, and its membership numbers have declined steadily over the past 75 years. But it is still seen as the most influential lobbying group advocating on behalf of America’s physicians.

One of Medicare-for-all’s great challenges is the unified industry opposition to single-payer; if that dam were to crack, even a little, that would be a significant victory for the cause. It didn’t quite happen this week, but the AMA vote suggests such a reversal isn’t entirely out of the question.

For now, the medical industry is lobbying hard against Medicare-for-all and placing its 2020 Democratic primary bets on former Vice President Joe Biden, a single-payer skeptic, to ward off the left’s crusade to overhaul the US health care system. In the near term, that may be a sound bet: Biden is leading in the polls, and Democratic voters seem to be prioritizing other issues and beating Trump over a 2021 legislative push to pass a Medicare-for-all plan.

But the winds do seem to be shifting — the House of Delegates vote is maybe the best evidence of the change yet. As Doherty tweeted: “There is a lot more support for publicly financed coverage than ever before.”