WASHINGTON — Sen. Bernie Sanders, I-Vt., usually regards incoming political fire as evidence that he's bombing the right targets — a sign that he's hitting adversaries where it hurts.

But not when some members of organized labor started picking at his Medicare for All plan in recent weeks because of fears that it would deprive them of high-end insurance policies obtained through negotiations with employers. Rep. Tim Ryan, D-Ohio, pressed Sanders on it during a presidential debate in Detroit late last month, and the issue has remained a hot topic for the candidates ever since.

That, Sanders seemed to realize, was a political problem he needed to address.

Here's what he offered unions this week: a federal regulation that would require employers to apply savings from Medicare for All to wages and benefits.

"Once Medicare for All is implemented, this labor rule, one part of Bernie's comprehensive plan to double union membership, is a simple assertion that under a Sanders administration, it will be the union worker, not the corporate employer, who will benefit from that savings," Josh Orton, national policy director for the Sanders campaign, said in an email to NBC News.

With that minor tweak, the iconoclastic Sanders executed a rare act of political dexterity to turn the narrative of him ignoring the pleas of his friends in labor on its head.

"I think it was very important politically," Rep. Ro Khanna, D-Calif., a national co-chairman of Sanders' campaign, said. "There was a misinformation campaign, and a cynical misinformation campaign, to imply Medicare for All would hurt union workers when it would help them."

He also left Sen. Elizabeth Warren, D-Mass., as the only leading Democrat with a Medicare for All plan that doesn't have a union carve-out and earned himself some badly needed attention in the national media.

Republicans and his rivals for the 2020 Democratic nomination called it a flip-flop, while Sanders' allies insisted it was simply a clarification of his existing position — he had previously said employers would pass savings on to workers without mentioning his plan to require that. But most important for him, unions welcomed the maneuver as part of a trend of candidates taking their concerns to heart.

"Labor’s positions have been clear and those are being reflected in candidates’ positions,” John Weber, press secretary for the AFL-CIO, said in a telephone interview with NBC News.

Sara Nelson, international president of the Association of Flight Attendants, said Sanders has long held his current position on savings being returned in wages or benefits, but that it is just now being understood because voters and members of the media are diving into the details of his policy for the first time.

Moreover, she said, the various proposals for expanding health insurance among Democratic candidates collectively provide a stark contrast with a yearslong Republican push to gut the Affordable Care Act, former President Barack Obama's health care law, in Congress and in the courts.

"There’s a very strong juxtaposition between all of the Democrats and the members of the GOP," she said in a telephone interview.

In interviews and text messages, several union officials said members are largely supportive of Medicare for All and similar proposals to shift toward a universal health insurance model — even if it means giving up private health insurance plans. The key question is the one Sanders sought to address: what happens to the money employers save.

Whatever the case — and it's one complicated by the diversity of opinion within unions, among them and between labor leaders and their own members — Sanders demonstrated an uncharacteristic willingness to adjust his course this week.

After Sanders ripped Sen. Kamala Harris, D-Calif., for criticizing a Medicare for All bill that she supported before changing to a revised version, her team reveled in media reports of a Sanders reversal.

"Team Bernie has no substantive answer for why they’re changing their M4A plan — and instead are going with 'attack the Washington Post' as the strategy," Harris spokesman Ian Sams tweeted.

Warren, who has come under the same criticism as Sanders, now stands alone among the major Democratic candidates in terms of supporting Medicare for All without a clear elucidation of what, if anything, she would do to assuage the concerns of labor unions.

In that way, Sanders may have boxed her in or created an easy bridge for her to follow him toward organized labor. Either way, at a time when they are close to each other in the polls and competing in similar ideological space on the political left, he moved first.

A Warren spokesman did not reply to a request for comment on whether she planned to stick with her policy approach.

Khanna noted that Warren has been known to say of her plan on health insurance, "I'm with Bernie."

"She should continue with that line," he said.

Though Sanders' campaign objected to the characterization of his proposed rule as a change in his Medicare for All plan, that was a shift from gripes that he wasn't getting enough attention from the media.

Fighting with the media over the nature of his coverage, with Republicans about ideology and with rival Democrats over purity is comfortable territory for Sanders. So is getting on the same page with labor unions — and that's where he finds himself now.

"Bernie is right to fix his plan to ensure unions maintain what they've bargained so members won't be worse off under a single-payer system," Randi Weingarten, president of the American Federation of Teachers, said in an email.