Democrats are gradually inching towards expanded government-sponsored healthcare, but in a time of GOP-controlled government, some wonder what the end goal is.

In a recent campaign ad, longtime centrist Sen. Dianne Feinstein, Calif., announced her support for lowering the Medicare eligibility age to 55 as well as renewed support for a government-controlled "public option."

"I believe in universal healthcare, in a public health option to compete with private insurance companies and expanding Medicare to everyone over 55," Feinstein, who is seeking a fifth term, said in the ad.

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Feinstein's shift is the latest move to the left by many moderate and centrist Democrats, who have been reluctant to adopt more progressive healthcare policies. Progressive groups and lawmakers are aiming for a single-payer, European-esque system, but coalescing the party around such a policy will take some work.

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Since the start of the Trump administration and Republicans' trifecta on the federal government, Democrats have mostly played defense on healthcare policy, particularly against planned cuts to Medicare and Medicaid, as well as efforts to dismantle the Affordable Care Act.

In recent months, various corners of the party have begun putting forward alternatives to Republican policies. However, the party as a whole has yet to consolidate around one path forward.

Proposed policies range from centrist-oriented, employer-offered Medicare-based insurance options and expanded Medicare eligibility to a progressive single-payer "Medicare for all" model. But one advocacy group says Democrats will eventually corral around one bill when push comes to shove, just as they did with the ACA.

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Eagan Kemp, a healthcare policy advocate at Public Citizen, an advocacy group that supports single-payer healthcare, told FierceHealthcare that Feinstein’s shift on policy signals a larger growing acceptance among reluctant Democrats to expand government-sponsored healthcare, which could eventually lead to the party accepting a "Medicare for all" system.

“Democrats are feeling pressure from the base to do more on healthcare,” Kemp added. “We are very happy with the level of support we’ve seen so far for progressive healthcare policies.”

House primaries are also indicating a growing acceptance of government-sponsored healthcare within the party. Amy McGrath in Kentucky's 6th district and Sean Casten in Illinois' 6th district are among the Democratic nominees in swing districts who support a single-payer system.

Kemp added that the 2018 elections hold a major key for progressive healthcare reform, even if the presidency is not in play.

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“If Democrats take back the House or Senate, lawmakers will certainly start having hearings on how to better define and shape what they want with single-payer and how to move forward on it,” he said, adding that such hearings will give reluctant Democrats more time to come around and support such legislation.

Such a position could auger well for some Democrats but not others. A recent Washington Post-Kaiser Family Foundation poll put support for single-payer at a slim 51% majority, with 43% being against, potentially putting moderate Democrats in red states in a difficult position.

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However, even Senate Democrats' most conservative member has said that a single-payer system should be looked at.

“It should be explored,” Sen. Joe Manchin of West Virginia told Bloomberg last year. "I want to know what happens in all the countries that have it—how well it works or the challenges they have."

Manchin, whose seat is considered vulnerable in this year's Senate elections, added that he is skeptical of such a system but all options need to be explored.

Senate map is rocky for Democrats

If a single-payer system is Democrats' endgame, the path forward is very narrow.

Democrats currently control 49 Senate seats and, in the best scenario, could pick up a maximum of two or three seats later this year, due to the party playing defense in 26 seats compared to the GOP's nine. Making matters more difficult for them, 10 of the seats Democrats are defending are in states President Donald Trump won in 2016.

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Even if the party is able to secure a majority in the Senate and House, and take back the White House in 2020, the GOP will continue to be their biggest obstacle. Republicans are sure to filibuster any single-payer legislation that is brought to the floor, which would require 60 votes to break. That scenario played out similarly during the passage of the ACA in 2010.

To get to 60 seats, Democrats would also need to gain between seven to eight seats in the 2020 elections, with the most opportunities in states Trump won in 2016—arguably a much more daunting task than what the party is facing this November.