FLINT, Mich. — Wherever he takes his campaign for governor, Abdul El-Sayed is followed by activists handing out information about “Medicare for all.” When he grabs the microphone, El-Sayed makes a promise: He’ll bring universal health care to Michigan.

“Why can the CEOs of big insurance corporations take home $13 million a year when 600,000 Michiganders still don’t have access to health care?” asked El-Sayed, who is a doctor, at a campaign stop last week in one of the state’s poorest cities. “When are we going to have leadership that stands up for statewide Medicare for all?”

El-Sayed, who campaigned this weekend with Sen. Bernie Sanders (I-Vt.) before Tuesday’s primary, is one of at least a dozen Democrats running for governor this year on a pledge to do what no state has ever done: give basic health insurance to everyone, no matter the cost.

The single-payer Democrats are on the ballot in red and blue states and from California, where Lt. Gov. Gavin Newsom is the heavy favorite to win in November, to Massachusetts, where Democrat Jay Gonzalez believes the issue will give him an opening against a popular Republican governor.

“We’re at a moment when Democrats need to stand for something,” Gonzalez said in an interview. “If we do this right, the total amount of money we spend on health care in Massachusetts should go down. We’re going to get from here to there in a very thoughtful way.”

The debate among Democrats is a continuation of the convulsions over health care that have marked politics for nearly a decade.

The passage of the Affordable Care Act in 2010 fueled a backlash that powered Republicans in that year’s midterm elections. The Trump administration’s attempts to unwind the law — including a lawsuit that would knock out popular protections for Americans with preexisting conditions — have put health care at the top of Democrats’ 2018 agenda.

Yet while Democrats running for the House and Senate talk about Medicare for all in aspirational terms, as a post-Trump national goal, liberal candidates for governor suggest that their states could quickly become laboratories for universal coverage. After years of bristling at questions about higher taxes and “government-run health care,” they’re leading with their chins — and the proposals they invite voters to read on their websites.

“There are going to be bills about this in dozens of states,” said Sam Munger, a spokesman for the liberal State Innovation Exchange who added that there has been a surge of single-payer legislation since the start of 2017. “Ninety percent of those bills won’t go anywhere, but people are pushing the spectrum of debate. Expanding health care, however they want to do it, is one of the top-testing messages we see in polls.”

Republicans, who are defending 26 governors’ mansions this fall, say they’ll benefit from the Democrats’ new mood. Republicans facing pro-single-payer gubernatorial candidates have attempted to define them as reckless, destructive spending addicts.

Last month, the Republican Governors Association began running TV ads against Ben Jealous, the Democratic nominee for governor of Maryland. “Tax-and-spend Ben Jealous,” according to the ads, would levy a “$2,800 fee for every man, woman and child.” Each attack tested strongly in Republican polling.

“Embracing an expensive single-payer health-care system could be a major drag on their campaigns, as it shows voters that they are fully supporting the significant tax hikes the system would require,” said RGA spokesman Jon Thompson. He predicted the ads would expand to other states.

Gov. Jay Inslee (D-Wash.), the chair of the Democratic Governors Association, said that Republicans were losing on the health-care issue and that attacks on single-payer amounted to diversions.

“Voters are much more interested in how Republicans want to take away your health care [tomorrow] — which is a legitimate fact — than something that might happen years from now,” he said.

Inslee suggested that Democrats were most convincing when they talked more incrementally about Medicare buy-ins, expanded Medicaid and other ways to build on the Affordable Care Act, rather than shifting to a new system.

Yet plenty of Democrats are pushing for more. In Colorado, where voters soundly defeated a single-payer ballot measure in 2016, Rep. Jared Polis (D-Colo.) has said that states could band together to provide universal health care.

“It’s not only the right thing to do, but the most cost-effective way to reform health care in the long-term,” Polis wrote in February. “I will work with other western states to tackle our shared health care challenges.”

While Polis and Newsom have already secured their party’s nominations, many of the candidates running on single-payer are insurgents challenging the party establishment and warning that it has been too timid as Republican governors have used their power to pass major conservative changes.

Cynthia Nixon, the actor challenging Gov. Andrew M. Cuomo (D-N.Y.) in a September primary, has endorsed the New York Health Act, which has been stuck in the state’s legislature.

Last week, the New York State Health Foundation estimated that the state would need to increase tax revenue by 156 percent to pay for the plan — but that it would save $2 billion in the long run.

Other candidates have talked up single-payer but skimped on the details.

In Connecticut, Ned Lamont has said that he would “champion a single-payer system” but at the national level.

In Rhode Island, gubernatorial challenger Matt Brown has promised to “create an expert commission of health-care and economic advisers,” which would hammer out details over time.

Andrew Gillum, the mayor of Tallahassee and an underdog candidate for Florida governor, has grabbed on to the single-payer brand but said Washington needs to be involved in implementing it.

“We know that Medicaid expansion and Medicare for all actually save this state and this nation $2 trillion if it were fully implemented,” Gillum said Thursday night in a Democratic primary debate. “We know that it’s a better public strategy. As governor I’d look forward to working with our colleagues in Washington to pursue that policy full on.”

The Trump administration, however, has attempted to preempt any discussion of state-based single-payer programs.

In a July 25 speech in California, the federal Medicaid and Medicare administrator, Seema Verma, said the administration, which has granted waivers for states to try conservative changes such as Medicaid work requirements, would deny waivers if states wanted to enact single-payer plans.

“You run the risk of depriving seniors of the coverage they have worked their entire lives to receive,” Verma said. “It doesn’t make sense to waste time on something that’s not going to work.”

Indeed, even in one of the biggest Democratic states, many have been skeptical about enacting universal health care.

Efforts to create a statewide system in California have foundered in the past two years in the Democratic-controlled legislature, beset by concerns about a cost estimated at $400 billion — twice the size of the current state budget.

In primaries, some center-left candidates for governor have similarly pointed out the practical difficulty of implementing single-payer and accused its advocates of prioritizing slogans over results. Gretchen Whitmer, the former state Senate leader who is ahead in Michigan’s polls, said in an interview that she soon would release a health-care plan and that El-Sayed — and Shri Thanedar, a wealthy businessman also running on single-payer — was not realistic about the stakes.

“I’m all for getting everyone covered. I always have been,” said Whitmer, whose TV ads promote her work on expanding Medicaid through the Affordable Care Act. “As the only candidate who’s actually gotten more people covered, I’m committed to that. I’m not going to go down the path of uttering magic phrases because we have to have a real plan. It’s not good enough to identify the problem.”

But El-Sayed, who left Detroit’s health department to run for governor, said that “MichCare” would be implemented over several years.

His campaign has published estimates of how much taxpayers would shell out in payroll taxes, contrasted with how much they’d save by no longer needing private health insurance.

An “average Michigan family,” it predicts, would see $38 taken out of their paychecks each month while saving $359 in health insurance in that time.

He predicted Democrats would flip control of the legislature in 2018 and strengthen their advantage for 2020 — “while we make the White House less orange” — putting themselves in a position to begin the process.

“People have to believe in government again,” said El-Sayed, adding that two successful years in Lansing would set the stage for Democratic victories in 2020, giving him more votes to advance single-payer.

Critics of such plans say that voters heard similar promises during Barack Obama’s presidency.

Most infamously, they heard it in Vermont, where three-term Gov. Peter Shumlin, a Democrat, bailed on a single-payer plan in 2014 after a study group found that it would require 11.5 percent payroll assessments on businesses.

“It is not the right time for Vermont,” Shumlin said then.

Sanders, readying his campaign stops with El-Sayed, said the problem was not the plan, and not the concept, but Shumlin himself.

“Vermont had a governor who was incapable of going for it and doing the right thing,” said Sanders, author of a federal universal health-care proposal. “Of course Republicans will try to frighten the American people about Medicare for all, like they tried to frighten them about Medicare, like they tried to frighten them about the ACA. You need people in the states who are going to lead.”