In an apparent concession to Bernie Sanders, presumptive Democratic candidate Hillary Clinton plans to back the creation of a "public-option insurance plan" under Obamacare and allow Americans at the age of 55 to enroll in Medicare.

Clinton's campaign announced the subtle platform shift in a statement Saturday, saying the proposals affirm the candidate's "career-long fight to achieve universal health care coverage for Americans." It is the first time she has formally endorsed a public option health care plan since entering the White House race.

The former secretary of state will "affirm her commitment to give Americans in every state the choice of a public-option insurance plan, something she has supported during this campaign and going back to her 2008 presidential campaign," the statement read.

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Of Medicare expansion, Clinton said she would also commit to "allowing individuals below the Medicare age to opt in to the program -- a proposal she first cosponsored legislation on in 2001 as a senator -- by providing the option to those 55 and older."

The campaign also promised that as president, Clinton would double funding for primary care services at medical clinics that primarily serve low-income communities.

"We have more work to do to finish our long fight to provide universal, quality, affordable health care to everyone in America," Clinton said in the statement. "Already, the Affordable Care Act has expanded coverage to 20 million Americans. As president, I will make sure Republicans never succeed in their attempts to strip away their care and that the remaining uninsured should be able to get the affordable coverage they need to stay healthy."

The Clinton proposals represent a further shift towards the policies of her Democratic primary rival, Vermont Sen. Bernie Sanders, who has yet to declare his support for Clinton's presidential candidacy -- though he has said he would still vote for the former secretary of state come November.

In a call with reporters Saturday morning, Sanders congratulated Clinton for the proposals and called it "a significant step forward" in expanding healthcare access for tens of thousands of Americans.

Sanders has said before that an endorsement for Clinton would only be forthcoming if she adjusted her policy platforms on health care, education, and minimum wage -- though source close to the Clinton campaign told CBS News Thursday that Sanders would endorse Clinton at an event in New Hampshire next week.

"I want her to say among other things, we have a crisis in higher education -- public universities and colleges should be tuition free. Raise the minimum wage to $15 an hour," Sanders told "CBS This Morning" in late June. "I believe that health care should be a right of all people. I would love her to say that and I would love her to move aggressively to make that happen."

Earlier this week, Clinton rolled out a new college affordability plan that seemed to take into account Sanders' own policy positions. The proposal would make public college tuition-free for families that make less than $125,000 per year.

While Clinton has not publicly backed a federal $15/hour minimum wage, the Democratic National Committee agreed late Friday night to include this proposal in their official party platform.