The plan is also a bid by Bloomberg — who declared his candidacy just three weeks ago — to get traction in a crowded campaign field. Bloomberg isn't one of the seven Democrats appearing at a joint PBS NewsHour/POLITICO debate Thursday night in Los Angeles, where health care is again expected to be a major issue.

Bloomberg's campaign said that a second forthcoming health plan, focusing on public health and drawing on Bloomberg's extensive record to combat smoking, obesity and other health risks, would be released in January.

What would the plan do?

Bloomberg's proposal would preserve existing private insurance plans while creating a government-run health insurance alternative. His plan, like the ones offered by former Vice President Joe Biden and South Bend, Ind., Mayor Pete Buttigieg also would boost subsidies to help people purchase coverage on the ACA marketplaces and limit the amount people pay for premiums. Separately, Bloomberg would create an optional Medicare benefit to cover dental, vision and hearing care for seniors, while requiring that Medicaid, the low-income health care entitlement, also cover dental care.

Meanwhile, the plan would roll back Trump administration efforts that health advocates say have weakened the safety net. Bloomberg is proposing to reverse Trump's expansion of association health plans and short-term plans, which his administration argues provide a lower-cost alternative to Obamacare coverage but have been criticized for weak protections for preexisting conditions. Bloomberg also would restore the Affordable Care Act's original 90-day open enrollment period, which Trump's health department cut in half, and ramp up outreach funding that the department also slashed.

Bloomberg’s plan also takes aim at politically powerful health care providers, calling for an end to "surprise" medical bills by requiring hospitals to provide care to insured patients at their in-network rates, regardless of which doctors see them. He’d also limit what health care providers could charge insurers, pegging their out-of-network prices to just twice the typically lower rates that Medicare pays.

Bloomberg also would boost resources devoted to rural health care by increasing federal grants to community health centers and requiring Medicare cover more telehealth visits, among other measures.

How would it work?

Bloomberg's public option is intended to boost competition in the individual insurance market, which would lower costs for all Americans, his campaign said. It's also intended as a "backstop" for millions of Americans in states that didn't expand Medicaid through the ACA and would instead get free coverage through Bloomberg's new option, a campaign official said.

Bloomberg also would create a federal reinsurance program, providing a financial backstop to health insurers with high costs. The Trump and Obama administrations have approved similar programs in some states, leading to cheaper premiums. Bloomberg's campaign said a nationwide program would reduce premiums by up to 10 percent in the individual market.

Meanwhile, Bloomberg calls for overhauling the nation's drug spending by allowing HHS to negotiate drug prices and capping those prices at 120 percent of the average paid in other developed countries. He would cap Medicare beneficiaries' out-of-pocket spending on drug costs at $2,000 per year.

Bloomberg also would move away from the nation's fee-for-service health care system, such as proposing a shift to fixed payments for rural hospitals. A campaign official said that Bloomberg's subsequent proposals will expand on ideas to limit payments to providers in exchange for quality improvements.

What are the weaknesses in the proposal?

Bloomberg's plan can't guarantee universal coverage. Some Americans might find that coverage remains too expensive, even with Bloomberg's proposal to cap premiums at 8.5 percent of income. The campaign also didn't detail whether Bloomberg would cover undocumented immigrants.

It's also unlikely to satisfy progressives — particularly the supporters of presidential hopeful Sen. Bernie Sanders (I-Vt.) — who have called for more sweeping reforms that would essentially eliminate private insurance.

Bloomberg's team also further dismissed the idea of "Medicare for All," arguing that single-payer health care would be a non-starter in 2021, given the likely Senate composition. "It's just not going to pass," said a campaign official, adding that Bloomberg's public option isn't intended as an eventual path to the single-payer system.

The plan assumes that Bloomberg will succeed where congressional Democrats have failed. Bloomberg's proposals to end "surprise" medical bills, strengthen the ACA and lower drug costs are similar to efforts that have stalled in Congress — sometimes because Democrats failed to support them. Asked how Bloomberg would achieve these goals, campaign officials pointed to the billionaire's decision to entirely self-finance his campaign.

“We’re not taking money from any of those interest groups,” a campaign official told POLITICO, arguing that donations have weakened congressional Democrats' resolve on key health care issues. "We think Mike can take a leadership role [and] if there was more leadership, we would see more movement on both drug pricing issues and surprise billing issues."

How much would it cost?

Campaign officials said the plan would cost about $1.5 trillion over a decade, citing studies by the Urban Institute and other outside analysts, and lead to roughly $500 billion in savings.

How would he pay for it?

Campaign officials said the plan's cost would be "primarily offset" by Bloomberg's proposals to cap provider payments, empower HHS to negotiate drug prices, end "surprise" medical bills and overhaul Medicare's prescription drug benefit. Bloomberg's public option would specifically be paid for by customer premiums, officials said.

Campaign officials also said Bloomberg would find additional revenue to pay for the health plan from other parts of the federal budget, promising to releasing a tax reform package and share more details in coming weeks.

What have other Democrats proposed?

Bernie Sanders

Elizabeth Warren

Joe Biden

Sanders has spent years pushing his Medicare for All proposal, which would virtually eliminate private insurers and require all Americans to enroll in government coverage. Warren has unveiled a two-stage Medicare for All proposal that she said would eventually lead to single-payer coverage.

Biden has proposed a public option to expand coverage and enhanced subsidies. His campaign estimated his plan would cover 97 percent of Americans.

Who would it help?

Bloomberg’s campaign said his proposal would help Americans who have been priced out of purchasing health coverage, hit with surprise medical bills or faced other financial pressures because of inadequate health coverage. Nearly 28 million Americans were uninsured last year and tens of millions more are “under-insured,” according to national survey data.

Who opposes it?

Health care providers have successfully fought — so far — Bloomberg’s ideas to limit their pricing power. Providers already have worked to slow congressional proposals to tackle surprise bills, which closely resemble policies in Bloomberg’s plan.

The Partnership for America’s Health Care Future, an industry-backed advocacy group, also has decried every Democratic candidate’s proposal to expand government-run health insurance. Government health insurers generally pay lower rates to hospitals, doctors and other health care organizations than private insurers.

Bloomberg's proposal to allow the government to negotiate drug prices also has been fiercely opposed by the pharmaceutical industry.