Sen. Bernie Sanders (I-Vt.) in Phoenix in 2015. (Charlie Leight/Getty Images)

Liberals are pushing in from the left with their own health-care solutions, looking to gain new ground after last week’s Republican meltdown over an Obamacare replacement.

The Progressive Change Campaign Committee, a political action committee that aims to represent the “Elizabeth Warren wing of the Democratic Party,” began circulating a petition Wednesday calling for every person to have access to a Medicare-type plan — an idea supported by the party’s left wing but viewed with some skepticism by moderates.

There’s broad agreement across the political spectrum that parts of the health-care law need fixing, most pressingly the premium spikes and insurer exits from the law’s insurance marketplaces. Liberal advocates and lawmakers see a fresh opportunity for rallying their side around the issue after House Republicans abruptly halted efforts late last week to repeal and replace the Affordable Care Act.

“I think Friday made it clear there is no consensus and no path forward from the right, and if there’s going to be a path forward it’s going to come from progressives,” said PCCC spokeswoman Kaitlin Sweeney.

Liberals still have little hope of enacting their solutions, with the GOP controlling the White House and Congress. But they’re trying to lay the groundwork for electoral victories in 2018 and 2020 that could open new doors.

“We are already working with our friends in Congress to build momentum for this idea — and make it a high-profile 2018 issue,” says the petition, which the group was emailing out Wednesday afternoon.

There are some small but notable signs that momentum is building for more government-run health insurance.

The House already had a single-payer bill in the form of HR 676, the Expanded & Improved Medicare For All Act, which Rep. John Conyers Jr. (D-Mich.) introduces in every Congress. Since the collapse of the GOP’s American Health Care Act, three new Democrats, Reps. Donald Payne Jr. (N.J.), Nydia M. Velázquez (N.Y.) and Peter A. DeFazio (Ore.), have signed on as co-sponsors, bringing its total number of endorsements to 75. The measure had just 62 co-sponsors when Conyers introduced it in 2015.

And over the weekend, Sen. Bernie Sanders (I-Vt.) introduced a single-payer bill; on Twitter, liberal activists had already been pressuring other senators to endorse it.

Republicans, reeling from the Obamacare fight, have highlighted the single-payer push as evidence that the Democrats will go too far.

“Obamacare is collapsing as a result of its top-down, government centered approach and the Democrats’ only answer is more government,” Jesse Hunt, a spokesman for the National Republican Congressional Committee said in a statement. “The question remains, how many other Democrats will join the chorus to appease the activist base of the Party that’s clamoring for far-left policies?”

But advocates and commentators on the left note that support for the idea of single-payer system is as high as it’s ever been. The PCCC petition points to a recent Pew survey showing that 85 percent of Democrats and 60 percent of Americans overall said the government is responsible for providing health coverage for all.

A Monday essay for the socialist magazine Jacobin by Harvard Medical School instructor Adam Gaffney argued that there was “no better time to fight for single-payer” than after the repeal fight revealed public support for wider coverage.

“Politicians have yet to follow the populace, but, with enough grassroots activism, they can be pressured and flipped, or — if recalcitrant — confronted with primary challenges or defeated at the polls,” Gaffney wrote. “The insurance industry will no doubt fight to the death, but it’s enormously unpopular, and surmountable.”