Related: Medicare for All: Where the 2020 presidential candidates stand

But many of the candidates — even official Medicare for All co-sponsors — are at the same time edging toward a more incremental approach, called “Medicare for America.” Proponents argue it could deliver better health care to Americans while avoiding political, budgetary and legal objections.

It comes as politicians tread carefully over the political land mines a Medicare for All endorsement could unleash, while seeking to capitalize on a growing appetite for health reform.

During the 2018 midterm election campaigns, some congressional candidates talked about allowing people older than 55 to join Medicare, or allowing people younger than 65 to buy into it if they choose (the “public option”). Many aren't eager to face the industry opposition that a full-on Medicare expansion would surely trigger.

From the consumer perspective, sweeping reform poses a risk. Despite Medicare's popularity with its beneficiaries, the majority of Americans express satisfaction with their health care, and many are nervous about giving up private options. Also, many analysts are worried that a generous Medicare for All plan that promises everything would break the bank without any patient payments.

That tension is pushing a number of candidates toward the emerging “Medicare for America” option. The bill was introduced last December to little fanfare by two Democrats, Rep. Rosa DeLauro (Conn.) and Rep. Jan Schakowsky (Ill.). It hasn't been reintroduced in the new Congress.

This proposed system would guarantee universal coverage, but leaves job-based insurance available for those who want it. Unlike Medicare for All, though, it preserves premiums and deductibles, so beneficiaries would still have to pay some costs out-of-pocket. It allows private insurers to operate Medicare plans as well, a system called Medicare Advantage that covers about a third of the program's beneficiaries currently, and which would be outlawed under Medicare for All.

“Before policies get defined, what you see is people endorsing a plan that is a little, perhaps, less subject to early attack,” said Celinda Lake, a Democratic pollster. “A lot of candidates feel if they endorse a plan that leaves some private insurance, they get more time to say what their ideas are about.”

“Medicare for America” got its first high-profile endorsement from former Texas Rep. Beto O'Rourke, who launched his own 2020 bid in mid-March. Other candidates — including Warren, Gillibrand and Pete Buttigieg, the mayor of South Bend, Ind. — have tiptoed toward it without making any endorsements, suggesting they back Medicare for All in theory but also support a system that retains private insurance, at least temporarily.

Such an approach is perhaps unsurprising. Polling indicates voters want strong health reform. Candidates, election experts say, need something powerful to deliver.

Improving the Affordable Care Act, an idea backed by Sen. Amy Klobuchar, a Minnesota Democrat running in the primary's moderate lane, may not suffice.

“The ACA is popular at the 50 percent level, but it's not energetic. It doesn't get people who really like it,” Blendon said. “What they're looking for is something that is exciting but isn't threatening.”

Both Medicare for All and “Medicare for America,” experts noted, offer something that presidential candidates can campaign on and a health alternative that at first blush sounds appealing to many. But the latter could skirt some potential obstacles.

Approval for Medicare for All drops when people learn that, under such a program, they would likely lose their current health plan (even if the government-offered plan could theoretically provide more generous coverage).

The cost-sharing element of “Medicare for America,” meanwhile, would ostensibly quiet some of the concerns about paying for Medicare's expansion, though critics on the left worry it would mean some people would still be unable to afford care.

This also tracks with recent polling which suggests that, while Medicare for All support can be swayed, voters of all political stripes favor some sort of way to extend optional Medicare coverage, without necessarily eliminating the private industry altogether.

Employers would have to offer plans that were at least as generous as the government program, or direct employees to Medicare. Employers who stop offering health benefits would have to pay a Medicare payroll tax.

For now, most candidates are still avoiding a concrete stance on “Medicare for America.” Despite signs of interest, the Buttigieg, Gillibrand and Warren campaigns all declined to directly answer questions about whether they endorse “Medicare for America.” The campaigns of other candidates in the race — Harris, Klobuchar, Booker, former Housing and Urban Development Secretary Julian Castro and Washington Gov. Jay Inslee — similarly declined to comment.

Reading between the lines, though, their promises to achieve universal health care by expanding Medicare — while retaining private insurance — leaves them few options besides something like “Medicare for America,” argued one of its main architects.

“There are variations besides this particular plan, but once you start to actually dig into this, if you want universal coverage you're going to have to do the kinds of things” spelled out in “Medicare for America,” argued Jacob Hacker, a political scientist at Yale University, who played a lead role in devising this proposal.

Still, though, it has prompted objections from both the left and the right.

On the far left, the cost sharing is a dominant concern. (Under “Medicare for America,” an individual would have a $3,500 out-of-pocket limit; a family would have a $5,000 limit. Premiums would be capped at almost 10 percent of a household's income.) Those critics also say the plan's accommodations to private insurance limit the government's ability to negotiate lower prices.

Conservatives repeat many of the arguments levied against Medicare for All — too expensive, too disruptive.

Hospitals, insurance, drugmakers and doctors, who have already mobilized against Medicare for All, also can be expected to make just as strong a showing against “Medicare for America,” political analysts said. More Medicare means less revenue for the medical industry.

Said David Blumenthal of the Commonwealth Fund: “The fact of expanded Medicare will be the focus of attacks.”

Kaiser Health News (KHN) is a national health policy news service. It is an editorially independent program of the Henry J. Kaiser Family Foundation which is not affiliated with Kaiser Permanente.

Read more: 

• White House report slams Medicare for All, talks up Trump administration reforms
• 4 approaches to expanding health care (and only one is Medicare for All)
• Trump says GOP 'blew it' on health care and must run on new plan