WASHINGTON — Sen. Richard Blumenthal has cast his lot with the Democratic Party’s progressive wing on a key issue, signing on Tuesday to Sen. Bernie Sanders’ “Medicare for all’’ measure that will be unveiled Wednesday.

“It is recognition that health care should be a right, and not a luxury,’’ said Blumenthal, D-Conn. “It would afford everyone the opportunity to buy into Medicare. It could be implemented step by step.’’

In backing the measure, Blumenthal joined a growing list of Senate liberal Democratic all-stars including Elizabeth Warren, D-Mass., Cory Booker, D-N.J., Kamala Harris, D-Calif., and Kirsten Gillibrand, D-N.Y.

Other Connecticut Democratic lawmakers have either looked askance at the Sanders bill or said they were mulling it over.

Sen. Chris Murphy “is still reviewing the legislation,’’ said spokeswoman Laura Maloney.

A spokesman for Rep. Jim Himes referred to a series of tweets on the subject that Himes wrote in June.

“Speaking for myself, this is the kind of massive change that requires serious and thoughtful consideration: hearings, town halls, SCORE,’’ Himes said, referring to the scoring typically done by the Congressional Budget Office that determines how much a piece of legislation will cost and what the impact will be.

Sanders will unveil the proposal on Wednesday as Congress continues to grapple with the aftershocks of Republicans’ failure to pass their own substitute for Obamacare. The narrow defeat in the Senate in July left President Barack Obama’s signature legislative achievement hanging by a thread, underfunded by a Republican-controlled Congress but still the only game in town.

“Medicare for all’’ would be voluntary. But it would undercut Obamacare over a four-year period, if not phase it out altogether.

As the name implies, the measure would make a Medicare-type government system available to all Americans. Medicare now provides government-subsidized health care to more than 55 million, the vast majority of them over age 65.

Republicans have castigated it as the ultimate in government-run health care. Critics have cited a study by the non-partisan Urban Institute projecting it would cost the U.S. government $32 trillion over 10 years.

Taxes could rise for individual households, but might be offset by lower premiums and health-care costs overall. The impact on employer-provided health care is uncertain.

Sanders himself has conceded his bill has little chance in the GOP-dominated Congress, telling NPR the purpose is to inject a single-payer system into the health care debate on Capitol Hill.

In endorsing the Sanders plan, Blumenthal insisted he wanted to see the current Obamacare markets stabilized as part of a gradual transition.

Asked whether the looming prospect of Medicare for all would actually destabilize the health-insurance markets further, Blumenthal said it was possible to accomplish both in sequence.

“Just because you know you’re going to buy a new car doesn’t mean you don’t fill the gas tank or fix a flat on the car you have now,’’ he said.