Sen. Bernie Sanders (I-Vt.) rolled out his “Medicare for all” health-care bill to much fanfare on Wednesday.

While the bill has no chance of passing in the current GOP-led Congress, it is a marker of where the Democratic Party is heading. 

Here are five things to know about the plan.

The plan could cover everybody, but with disruption

The goal of the plan, as the name “Medicare for all” suggests, is to provide health insurance for everyone in the country. And it could achieve that goal, covering the roughly 28 million people who remain uninsured even under ObamaCare. 

But a universal system could come with serious tradeoffs. For one, the cost of Sanders’s plan is not yet clear. Transitioning to such system would mean upending health coverage for tens of millions of people, particularly those who get coverage through their jobs.

“You try prying loose [coverage] from people who are doing better than they would be under this shift,” said Tom Miller, a health-care expert at the right-leaning American Enterprise Institute.

It’s unclear how it would be paid for, or how much it costs

Sanders’s proposal does not yet have a price tag, but it is sure to be large, and a key point of attack for Republicans.

The Urban Institute estimated that a previous plan from Sanders last year would cost $32 trillion over 10 years. 

Sanders did put forward a range of options for how to pay for his plan, but has not settled on one. The options include a new 7.5 percent payroll tax on employers or raising taxes on the wealthy or large banks.

Nailing down the details on the financing is a key obstacle. John McDonough, a Democratic Senate health staffer during the passage of ObamaCare now at Harvard’s school of public health, noted that Vermont’s effort at state-level single-payer fell apart in 2014 over the question of how to pay for it.

“They looked at the tax increases that would be required and they pulled the plug,” McDonough said. “Any plan that lacks financing is not yet baked.”

It would provide very generous coverage

Despite the name “Medicare for all,” the coverage in the plan would be more generous than what is now provided under Medicare. While the current program has deductibles and other costs that consumers have to pay, the Sanders plan would provide health services at no upfront cost to the patient.

The plan would cover a wide range of services, including vision care, mental health and dental care.

Experts fear such generous coverage, with no co-pays or deductibles from the patient, could drive up national healthcare spending. If people don’t have to pay when they go to the doctor or use health services, the thinking goes, they will go to the doctor more often.

“Covering everyone and eliminating deductibles and copays would push spending up,” said Larry Levitt, a health policy expert at the Kaiser Family Foundation.

Levitt said it is “not at all clear” whether the Sanders plan would end up saving money and reducing overall national health spending.

Vulnerable Democrats are steering clear

Politically, the Sanders plan has more support than it has ever had before, with 16 Democratic senators joining Sanders in sponsoring the plan.

But Democrats who face tough reelection races are largely staying away.

“We also have to realize that we have not figured out cost containment and it’s what’s driving our debt right now, and we’ve got to work on that before we expand our system,” said Democratic Sen. Claire McCaskill, who is up for reelection next year in Missouri.

Added Sen. Jon Tester (D-Mont.), another senator facing reelection: “I support fixing what we’ve got, because I think that’s more likely to happen.”

Possible presidential candidates are lining up to support it

On the other hand, many Democrats eyeing a run for president in 2020 are enthusiastically backing Sanders’s proposal.

The support shows how much of a shift there has been among Democrats toward single-payer, despite their continued support for ObamaCare.

Sens. Kamala Harris (D-Calif.), Cory Booker (D-N.J.), Kirsten Gillibrand (D-N.Y.) and Elizabeth Warren (D-Mass.) all announced their support for Sanders’s bill.

“All should receive the healthcare they need regardless of where they live, their income, or their ZIP code,” Harris said. “And that’s what this bill is about.”