Progressives are pushing Medicare for All in some of the Democratic Party’s most competitive Senate primaries next year, threatening the unity the party has found on attacking Republicans over expiring Obamacare subsidies.

In Maine, Graham Platner said he’s making Medicare for All a “core part” of his platform in his race against Gov. Janet Mills, the establishment pick who’s called for a universal health care program. In Illinois, Lt. Gov. Juliana Stratton and Rep. Robin Kelly are both championing the concept — and calling out rival Rep. Raja Krishnamoorthi for not fully embracing it.

In Minnesota, Medicare for All has emerged as a key distinction between progressive Lt. Gov. Peggy Flanagan and moderate Rep. Angie Craig, who supports adding a public option to the Affordable Care Act rather than Medicare for All. Flanagan said she “absolutely” expects the policy to define the primary because “it doesn’t matter if I’m in the urban core, the suburbs or greater Minnesota — when I say I’m a supporter of Medicare for All, the room erupts.”

And it’s become a flashpoint in Michigan, where physician Abdul El-Sayed, who wrote a book called Medicare for All: A Citizen’s Guide, is using his signature issue to draw a contrast with Rep. Haley Stevens and state Sen. Mallory McMorrow, who favor other approaches.

Medicare for All — government-funded health coverage for every American — is “where we need to point to,” El-Sayed said in an interview. “And I think you can galvanize a winning coalition around this issue.”

But some more moderate Democrats worry that progressives’ renewed push for Medicare for All would undermine the party’s recent united front in fighting for an extension of the Obamacare subsidies that are set to expire at the end of the year, leading to a significant spike in insurance costs for millions of Americans. Their effort initially failed in the Senate, but with the help of four vulnerable Republicans who crossed party lines this week, Democrats have now secured a House vote on an extension in January.

“We have a singular message, which is: ‘Don’t let these tax credits go.’ We have Republicans on the ropes,” said a national Democratic strategist who works on Senate races and was granted anonymity to speak candidly. “I don’t think introducing ‘we need MFA’ is the right strategy right now. I think it would be unhelpful.”

Several Democratic consultants pointed to recent public polling showing Americans like having individual insurance coverage, despite being dissatisfied with health care companies. An NBC News poll found 82 percent of Americans were satisfied with their plans, both private and government-sponsored. Based on that data, these consultants said allowing Americans to buy into a government-offered plan, known as a “public option,” is more politically palatable.

Centrists have long dismissed Medicare for All as both a policy pipedream and political albatross for their party — a rallying cry for the left that serves as catnip for Republican admakers looking to broad brush Democrats as socialists. They argue that surveys often fail to present voters with the full picture of how Medicare for All would work, and therefore fail to capture its electoral toxicity.

“What we need to accept is there’s a deeply held skepticism among Americans about going zero to 60 that’s entirely government run, even though they don’t love the current system,” said Adam Jentleson, a Democratic strategist and president of the Searchlight Institute. “In isolation, this thing does okay. But it’s not how it plays out in real life, and the totality will crush us.”

The once-fringe policy that Sen. Bernie Sanders (I-Vt.) mainstreamed during his presidential campaigns has become a rallying cry for his favored candidates and other progressives across battleground primaries, as Democrats work to make health care costs central to next year’s midterms and as the party base clamors for fighters willing to disrupt the status quo. The push for Medicare for All, which receded during the more moderate Biden era, comes as Democrats have otherwise been unified on their health care messaging, forcing Republicans onto defense over their refusal to extend expiring Affordable Care Act subsidies.

“Do I think every single swing-seat candidate is going to come out for Medicare for All? No,” said Jess Morales Rocketto, a Democratic strategist and board member for the nonprofit Care in Action. “But if you want to signal that you’re unafraid and bold right now, and you want to say you’re not beholden to the status quo, it’s a perfect position for that.”

Progressives are emboldened by partisan and independent polling that shows most Democrats and a majority of independents support Medicare for All. A recent survey commissioned by Rep. Pramila Jayapal’s (D-Wash.) leadership PAC and first reported by Blue Light News showed 90 percent of Democrats back Medicare for All and found most independents and one in five Republicans back a “government-provided system.”

Jayapal, the former chair of the Congressional Progressive Caucus, plans to push her colleagues to start promoting Medicare for All again in the new year. She predicted in an interview that support for the system will be a “defining factor” in the party’s primaries next year and an electoral winner in battleground House seats.

But proponents of Medicare for All argue that a government-provided system would lessen the pinch of rising health care costs. They say pushing to extend the ACA subsidies and promoting Medicare for All as an end goal are not mutually exclusive. And they point to several 2018 candidates who won tough seats while supporting the measure, including former Rep. Katie Porter in California to retiring Rep. Jared Golden of Maine.

“You can know that there are short-term stopgaps that must be taken to protect working people while also thinking that long term, we need a better system,” said Platner, who is vying against Mills to unseat GOP Sen. Susan Collins in Maine.

Platner has been extolling Medicare for All from the start of his campaign and said it gets the “most raucous” response at his events across Maine, where a recent Pan Atlantic Research poll found 63 percent support for the system (and Platner trailing Mills by 10 points).

He argued in an interview that Mills isn’t as steadfast in her support for the concept because she “doesn’t talk about it all that often” and uses “vague language” when she does. Mills has said “it is time” for universal health care and that she’s “committed to finding a way to get there” if elected. Her campaign echoed that sentiment in response to a request for comment for this story, and cited her efforts to expand Mainers access to Medicaid.

In Minnesota, Flanagan said embracing Medicare for All has been a “journey” during her Senate campaign, as she heard from Minnesotans that the “cost of health care is the thing that comes over and over and over again.” Of Craig’s support for a public option, Flanagan said voters don’t want a nominee who “nibbles around the edges” instead of being “bold and audacious.”

Craig calls the public option a “big, bold reform,” but emphasizes that it’s a policy “we could actually accomplish in this country in a fairly short time period,” she said in a video this week.

In Illinois, Stratton and Kelly, two of the three leading Democrats vying to replace retiring Sen. Dick Durbin, are jockeying for position as Medicare for All’s biggest champion in the race while their campaigns knock Krishnamoorthi for couching his support for the system. Krishnamoorthi said in a statement that while it’s “a noble goal, and I’m fighting to get us to universal coverage” his focus is on extending the ACA subsidies and reversing Republicans’ cuts to Medicaid.

And in Michigan, El-Sayed has slammed McMorrow’s call for universal health care with a public option as “incoherent” and ill-informed as the two compete for the same slice of progressive voters. McMorrow has knocked the idea of a single-payer system run by President Donald Trump and his controversial health secretary, Robert F. Kennedy Jr. And she’s promoted a public option so people who like their private insurance can keep it. Stevens’ campaign says she supports strengthening Obamacare, including through a public option, without endorsing Medicare for All.

The issue is also becoming a flashpoint in Democratic primaries for some of the most competitive House seats in the country, driven in part by Sanders-backed candidates running from California’s Central Valley to Pennsylvania’s Lehigh Valley.

“There’s immense hostility and anger toward the way the insurance industry functions, doubled up with health care itself being one of the biggest affordability issues,” said Mark Longabaugh, a progressive strategist who worked on Sanders’ 2016 presidential bid. “Progressives are smart to push the case.”