Bernie Sanders' "Medicare for All" push has upended Democratic politics almost as thoroughly as it would upend the health care system.

Why it matters: The coverage most of us are used to — private insurance through the workplace — would change or even disappear under Medicare for All. The only question Democrats are really debating is how far to go, and how quickly.

Driving the news: Sanders will introduce a new version of "Medicare for All" today that's even more ambitious than his last one — which was already more ambitious than any other health care system on Earth.

If something like Sanders’ bill did become law, it would “leapfrog the rest of the world,” as the Kaiser Family Foundation’s Larry Levitt put it.

did become law, it would “leapfrog the rest of the world,” as the Kaiser Family Foundation’s Larry Levitt put it. It would be the most robust system in the world, and one of the most centralized — a sea change from today's largely privatized patchwork.

What it would mean for you: Sanders’ plan would move almost everyone — whether you’re on Medicare or Medicaid, or buy insurance on your own through the Affordable Care Act, or get it through your job — into a single government-run program.

You could not keep your existing plan.

your existing plan. You could keep your doctor. When the Affordable Care Act made some people switch doctors, it's because they had to switch insurance plans, and each plan has its own network of doctors and hospitals. With a single national plan, though, there are no networks.

your doctor. When the Affordable Care Act made some people switch doctors, it's because they had to switch insurance plans, and each plan has its own network of doctors and hospitals. With a single national plan, though, there are no networks. Coverage would be incredibly generous. Sanders' program would cover just about everything, including vision and dental, all with no premiums and no out-of-pocket costs (like copays and deductibles) — unlike today's private insurance.

Sanders' program would cover just about everything, including vision and dental, all with no premiums and no out-of-pocket costs (like copays and deductibles) — unlike today's private insurance. Taxes would go up. A lot. That’s the tradeoff for eliminating premiums and deductibles. Sanders has not said which taxes he would raise.

A lot. That’s the tradeoff for eliminating premiums and deductibles. Sanders has not said which taxes he would raise. Overall spending would be about the same as what we’re expected to spend under the status quo, according to multiple estimates. We'd just pay for it differently. Today's hodgepodge of premiums, copays and state and federal spending would all be rolled into one federal, taxpayer-funded program.

Yes, but: This is Sanders' plan as written. It would need several political miracles to pass, especially in this pure form. And even then, it would still need sustained political support to keep functioning the way Sanders intends.

The other side: The leading alternative to Sanders’ proposal, known as “Medicare for America,” would move more gradually and is not quite as robust as Sanders’ version — but would still be enormously different from what we have now.

How it works: A new public program would automatically absorb the uninsured, all newborns, and everyone on Medicare, Medicaid, and the Affordable Care Act’s exchanges.

This version would be optional: Employers could keep offering coverage on their own, or pay to cover their workers through the public plan.

Employers could keep offering coverage on their own, or pay to cover their workers through the public plan. So your plan could change if your employer opted into the new system, and that means your doctor could, too. ( Reminder: employers can already change their plans today.)

if your employer opted into the new system, and that means your doctor could, too. Reminder: employers can already change their plans today.) Over time, as more employers opt into the public system and people covered as newborns age into the workforce, “I think it’s a reasonable assumption that the employer market would deteriorate," Levitt said.

as more employers opt into the public system and people covered as newborns age into the workforce, “I think it’s a reasonable assumption that the employer market would deteriorate," Levitt said. This new version of Medicare would still have a role for private insurers, similar to what Medicare has now. They could create their own networks of doctors and hospitals.

of Medicare would still have a role for private insurers, similar to what Medicare has now. They could create their own networks of doctors and hospitals. Your costs: Middle- and upper-income households would still need to pay a premium, and some out-of-pocket costs. Both would be capped based on income. This means the tax increases would likely be lower than Sanders’ plan.

The big picture: The U.S. health care system is by far the most expensive in the world, and yet despite that spending, we have worse health outcomes than similar countries. We're also an outlier among other rich countries because we don't guarantee coverage to everyone.

Sanders' plan to blow up that system is what forced the issue onto Democrats' front burner — and he's not looking to back down now on the specifics.

The bottom line: You might love the new system or you might hate it — but either way, "if you like your plan, you can keep it" is not a promise you're likely to hear from Sanders.