A major liberal policy group is raising the ante on the health care debate with a new plan that builds on Medicare to guarantee coverage for all.

Called "Medicare Extra for All," the proposal to be released Thursday by the Center for American Progress gives politically energized Democrats more options to achieve a long-sought goal.

Still, the plan would preserve a role for employer coverage and for the health insurance industry. Employers and individuals would have a choice of joining Medicare Extra, but it would not be required.

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That differs from the more traditional "single-payer" approach advocated by Vermont independent Sen. Bernie Sanders, in which the government would hold the reins of the health care system.

Even though the plan has no chance of passing in a Republican-controlled Congress, center president Neera Tanden said, "We think it's time to go bolder. There is consensus on the progressive side that universal coverage should be the goal and health care is a right."

Picking up on the leftward shift among Democrats, Republicans are already working up rebuttals. President Donald Trump tweeted earlier this month that "Dems want to greatly raise taxes for really bad and non-personal medical care. No thanks!"

The Center for American Progress is a think tank that was closely aligned with President Barack Obama and 2016 Democratic presidential nominee Hillary Clinton. A 2005 proposal from the center foreshadowed Obama's Affordable Care Act.

Medicare Extra would use Medicare's thrifty payment system as framework to pool working-age people and their families, low-income people now covered by Medicaid, and seniors. A major missing piece: There's no cost estimate for the plan, although its authors say that's in the works.

The proposal comes at a time when polls show intense interest among Democrats and some independents in a government-run system that would guarantee coverage and benefits while reducing the complexity and out-of-pocket costs associated with private insurance. The future of health care is expected to be a defining issue in the 2020 Democratic presidential primaries, and political messages will be tested and honed in this fall's midterm elections.

A nonpartisan expert who independently reviewed the Medicare Extra plan said it could provide Democrats with a middle way to achieve their longstanding goal of coverage for all.

"It's an attempt to capture the enthusiasm for a single-payer system among the Democratic base, but trying to create a more politically and fiscally realistic roadmap," said Larry Levitt of the nonpartisan Kaiser Family Foundation.

To be sure, taxes would rise and the federal government would take on a larger role.

"It is in some ways 'repeal and replace,' but from the left rather than the right," Levitt added.

Medicare Extra envisions a complex transition that would take the better part of a decade. Among its major elements:

—All U.S. citizens and lawful residents would be automatically eligible for coverage.

—Preventive care, treatment for chronic disease, and generic prescription drugs would be free. Dental, vision and hearing services would be included.

—Low-income people would pay no premiums or copays. Premiums and cost-sharing would be determined according to income for everyone else.

—Employers would have the option of maintaining their own plans or joining Medicare Extra. Workers could pick the government plan over their employer's. The proposal would preserve the tax-free status of employer-provided health care, subject to a limit.

—Seniors with private Medicare Advantage insurance plans through Medicare would be able to keep similar coverage, although the program would be redesigned and called "Medicare Choice." Seniors would gain coverage for vision, dental and hearing services not now provided by Medicare. Long-term care services would be covered.

—Government would negotiate prices for prescription drugs, medical devices and medical equipment.

Although costs and financing are not spelled out in the proposal, its authors acknowledge significant tax increases would be required. Options include rolling back some of the recently enacted GOP tax cuts for corporations and upper-income people, raising Medicare taxes on upper-income earners, and higher taxes on tobacco and sugary soft drinks.