WASHINGTON Democratic leaders in Congress are offering to cooperate with Republicans on solutions to stabilize the Obamacare exchanges, but progressive groups and their congressional allies are heading in the opposite direction.

Following the defeat of Republican efforts to repeal the Affordable Care Act , or Obamacare, left-leaning organizations are accelerating their long-standing goal of establishing a single-payer system in which the government provides health insurance for all.

Although proponents of what they call Medicare for all acknowledge that such a radical overhaul of the health care system is impossible as long as Republicans control the White House and Congress, they want it to become a litmus test for 2020 presidential candidates and a winning issue for as many 2018 congressional candidates as possible.

That way, the thinking goes, when Democrats return to power, they will recognize that single payer, or a number of interim steps favored by advocates, is the only politically viable health care policy.

The Democratic position has to be guaranteed health care with single-payer financing, said Michael Lighty, director of public policy for National Nurses United, a 150,000-member labor union that has been at the forefront of single-payer advocacy. The activists who volunteer for campaigns and put their heart and soul into the party, arent going to be satisfied with anything less than Medicare for all.

All Democrats who have any aspiration to run for national office must support Medicare for all, said Murshed Zaheed, political director of Credo Mobile, a phone company that channels its revenue into progressive online organizing. That automatically puts certain people Cory Booker , Kamala Harris and Kirsten Gillibrand, for example on the spot: Are they going to support Medicare for all or not?

On Friday, Credo launched an email campaign asking activists to sign a petition telling all Democrats running for national office: Support Medicare for All. The group plans to gradually send the appeal to its entire email list of more than 5.7 million people.

The goal, Zaheed said, is to make opposition to single payer as politically radioactive for 2020 Democratic presidential candidates as support for the Iraq War was in the 2008 primary. In Democrats 2008 nominating contest, then-Sen. Barack Obama s opposition to the war from its outset helped him defeat then-Sen. Hillary Clinton , who had voted to authorize the invasion in 2002.

At the same time, Zaheed said, they welcome more modest proposals that lay the foundation for full, publicly provided coverage, including the creation of a public health insurance option, lowering the Medicare eligibility age and expanding Medicaid.

Were not going to pooh-pooh them and say No, no, we want Medicare for all. We will say it is a great starting point, he said.