Supporters hold signs as Sen. Bernie Sanders (I-Vt.) introduces Medicare-for-all legislation. (Aaron P. Bernstein/Reuters)

Liberal Democrats’ goal of transforming the U.S. health-care system into a single, government-financed model would be “complicated, challenging and potentially disruptive,” Congress’s budget analysts caution in a report.

The analysis, issued Wednesday by the Congressional Budget Office, offers a reality check on the campaign slogans that have characterized a growing crop of Democratic presidential aspirants who champion the idea of Medicare-for-all.

The report lays out “opportunities and risks” of moving every American into a single government plan that covers all or most medical services. On the plus side, it says, such a plan would produce universal coverage and probably a more efficient health system. Among the negatives: higher government spending and taxes — and potentially longer waits for some treatments and technologies.

The report says the government would have to figure out how to pay for virtually all of the nation’s $3.5 trillion in annual health-care expenditures, inheriting the nearly half now absorbed by private employers and consumers. Whether overall health-care spending would rise or fall — and how many of the 29 million uninsured residents would gain coverage — hinges on complex choices that policymakers would confront, the report says.

The sober CBO tutorial was requested by House Budget Committee Chairman John Yarmuth (D-Ky.) in January, days after Democrats took control of the chamber. A past co-sponsor of Medicare-for-all bills, Yarmuth says lawmakers should begin to wrestle with the complex policy choices involved in transforming a health-care system that accounts for one-sixth of the U.S. economy.

The 29-page report does not estimate the cost of any specific legislation. Instead, it maps out many detailed decisions lawmakers would have to make, each carrying big stakes. Those include what medical services would be covered, how much doctors and hospitals would be paid, how much patients would chip in, whether private insurance companies would still exist, and how increased taxes would be designed.

The ripple effects, the report said, are hard to predict. Wait times to see a doctor could increase, depending on whether physicians stopped practicing medicine if payments for care were reduced. On the other hand, the bloated U.S. health-care system could become more efficient, assuming a redesigned system would have lower administrative costs than those of private insurers and heightened incentives for patients to get preventive care.

The analysis arrives as several of the most liberal 2020 candidates support single-payer arrangements — often without offering many details.

Party moderates support less far-reaching ways of letting more people get insurance through Medicare, the popular federal insurance program for older Americans, or other approaches to shrink the large number of Americans who remain uninsured. House Speaker Nancy Pelosi (D-Calif.) has made clear she would prefer to improve upon the Affordable Care Act, the sprawling 2010 health-care law that has extended coverage to roughly 20 million people.

Meanwhile, the term Medicare-for-all has become a whipping post for Republicans, including members of the Trump administration. Hours before the release of the much-anticipated report, GOP members of the House Budget Committee put out a video calling Medicare-for-all “radical” and “really expensive,” with conservative health-policy experts saying that it would swell the federal budget without a means to pay for it.

On Wednesday, Yarmuth, the House budget chairman, thanked the CBO for the analysis and predicted it would help advance his goal. “It is no longer a matter of if we will have a single-payer health care system in our country, but when,” he said in a statement.

The political hurdles also were quickly evident from industry reaction to the report. Charles N. “Chip” Kahn III, president of the Federation of American Hospitals, called a single-payer system “a high-stakes gamble” asking, “Is it worth the risk of upending health care for every American when the law on the books already contains a road map to universal coverage?”

Yarmuth said he will convene a hearing on the idea of a single-payer system later this month. It will be a sequel to a first-ever Medicare-for-all hearing held Tuesday before the House Rules Committee, focused on a measure introduced by Rep. Pramila Jayapal (D-Wash.), that would eliminate private health insurance within two years and extend coverage to everyone — with the government picking up virtually the entire bill. Her legislation does not spell out what the new system would cost or how it would be paid for.

Other bills that would expand Medicare to varying degrees have also been introduced.