Sharp disagreements among the presidential hopefuls at this week's debates have crystallized a critical and explosive political question: Are Democrats willing to upend health coverage for tens of millions of their fellow Americans?
The party is closer than it's been in decades to embracing a healthcare platform that would move all Americans out of their current insurance and into a single government-run plan.
Plans pushed by three of the four leading candidates — Sens. Bernie Sanders of Vermont, Elizabeth Warren of Massachusetts and Kamala Harris of California — differ in their particulars but would all end the job-based system that provides coverage to more than 150 million people.
That's a hugely risky strategy, as more-centrist rivals reminded the three senators during the two nights of heated, sometimes confusing, debates.
Sweeping healthcare plans have never fared well in American politics.
For decades, voters repeatedly have punished presidents and Congresses — Democratic and Republican alike — who have threatened to take away existing health plans, no matter how flawed.
Just last year, the GOP suffered historic losses in the House of Representatives after the party's unsuccessful effort to roll back the 2010 Affordable Care Act, also known as Obamacare.
But at a time when rising insurance deductibles and medical bills are crippling growing numbers of American families, many Democrats on the party's left believe public discontent with the current system has changed that dynamic.
"It's time that we separate employers from the kind of healthcare people get," Harris said Wednesday night, acknowledging that her "Medicare for all" plan would, after a lengthy phase-in period, end job-based insurance.
Harris, Sanders and Warren have made Medicare for all a central plank of their campaigns, riding a wave of discontent over rising medical costs to call for a historic expansion of government insurance.
Their more-moderate rivals say the three have misjudged the public mood and that by overreaching, they would squander an opportunity to enact significant, if incremental, reforms.
A survey earlier this year by the nonprofit Kaiser Family Foundation found that support for a single government plan fell from 56% to 37% when respondents were told that it might involve eliminating private insurance companies or requiring more taxes.
"It doesn't make sense for us to take away insurance from half the people in this room," warned Colorado Sen. Michael Bennet, who is among many Democratic presidential candidates, including former Vice President Joe Biden, who back more limited approaches.
The more-centrist Democrats would preserve the current employer-based system, as well as state Medicaid programs and the insurance marketplaces created by the 2010 healthcare law.
They would add an additional choice to allow Americans to buy into a Medicare-like government plan, often called a "public option."
"Every single person in America would be able to buy into that option if they didn't like their employer plan," Biden said Wednesday.
Critics on the left say that approach would ultimately cost more and would preserve an outsized role for private insurance companies.
"We have tried this experiment with the insurance companies," Warren said from the debate stage Tuesday. "And what they've done is they've sucked billions of dollars out of our healthcare system. And they force people to have to fight to try to get the healthcare coverage that their doctors and nurses say that they need."
But threatening Americans' current health coverage has proved disastrous for previous Democratic efforts to expand protections, including President Clinton's doomed initiative in the early 1990s.
The 2010 healthcare law was almost sunk by labor unions angry about a new tax on the kind of generous health plans many of their members enjoy.
And even though the law was designed to have minimal impact on the existing insurance system, President Obama faced a firestorm when a few million people found their health plans canceled after new rules took effect requiring plans to offer more-comprehensive benefits.
"Traditionally, fear of losing benefits — however flawed they may be — trumps hope of getting something better," said Chris Jennings, an influential Washington health policy advisor who worked for Clinton and Obama.
Even Republican politicians have paid steep prices for proposing to disrupt the employer-based health insurance system.
When Arizona Sen. John McCain, the 2008 GOP presidential nominee, proposed a new system to give Americans tax credits to buy their own health plans instead of getting coverage through work, he was pilloried by then-candidate Obama.
Obama made the McCain proposal a centerpiece of his advertising strategy attacking the Republican nominee.
To be sure, as deductibles soared, more than tripling in the last decade, job-based health benefits have offered workers less and less protection, generating political anger.
More than half of Americans in an employer-provided plan report they or an immediate family member have delayed getting medical care because of costs in the previous year, according to a nationwide poll conducted last year by the Los Angeles Times and the Kaiser Family Foundation.
One in six said they had made a difficult sacrifice in the previous year to pay for healthcare, such as cutting back on food and other essentials.
The poll also found substantial anxiety among lower-income workers and those with the highest deductibles, with 4 in 10 reporting frustration with their coverage, and nearly a quarter saying they're angry.
Backers of Medicare for all highlight these struggles in their calls for major change.
Medicare-for-all plans promise much lower out-of-pocket costs for American patients, eliminating high deductibles and premiums, but would raise taxes for some.
But even as millions of workers struggle with medical bills, most continue to express satisfaction with their health benefits, a paradox that has long characterized Americans' views about healthcare.
Overall, close to three-quarters of U.S. workers with job-based coverage said they feel grateful, the Times/Kaiser Family Foundation poll found.
"Americans are famous for holding contradictory opinions," said Mollyann Brodie, who oversees Kaiser's polling. "This challenge illustrates the fundamental dilemma in getting people to trust the promise of lower costs and better benefits under a brand-new system."
The incremental healthcare strategy pushed by the moderates hews more closely to the country's political tradition.
Medicare and Medicaid covered far fewer people when the programs were created in the 1960s, but Democrats and Republicans gradually expanded eligibility for the government health plans, adding patients with kidney failure, poor adults without children and others over the years.
Similarly, Clinton and a Republican Congress created the Children's Health Insurance Program in the late 1990s amid concerns about uninsured children from working-class families who made too much to qualify for Medicaid.
And the 2010 healthcare law focused on closing remaining gaps, providing money to states to expand their Medicaid programs further and establishing regulated marketplaces for Americans who didn't get health benefits at work.
Whether an incremental approach will suffice this year for an angry Democratic electorate remains unclear.
"The public's outrage and frustration with the cost and complexity of our current healthcare system … including employer-based coverage,"Jennings said, "is opening the door for change and closing it on those who are perceived as status quo defenders."