In a landmark agreement to expand California's Medicaid program, state lawmakers struck a deal this week with Democratic Gov. Gavin Newsom to cover the health care costs of an estimated 90,000 non-citizens living without legal permission in the Golden State.

Their unprecedented move could also sway the 2020 debate over universal health care, as Democratic presidential candidates court votes in the delegate-rich Super Tuesday state.

"Immigrants are an incredibly important part of our society and economy, and should be all fully included in our health system in this same way," Anthony Wright, executive director of the Health Access coalition in California, tells CBS News.

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"This is a dramatically different direction to the Trump administration, to actually provide coverage further and get to the goal of an affordable, accountable, and universal health system," Wright added.

Nearly every Democratic White House hopeful has vowed to seek some kind of universal health coverage, whether through "Medicare for All," which would expand the health care system that covers older Americans to everyone, or other plans that build on the Affordable Care Act. Among them, few have staked out positions on whether their policies would cover all those living in the United States, regardless of their immigration status.

During his last presidential bid in 2016, aides to Sen. Bernie Sanders told Politico that his single-payer proposal encompassed "everyone, including aspiring Americans."

Reintroduced this year, the Vermont independent's Medicare-for-all bill aims to do the same by guaranteeing eligibility to "every individual who is a resident of the United States." Five other Democratic presidential candidates -- Sens. Cory Booker, Kirsten Gillibrand, Kamala Harris, and Elizabeth Warren -- have all cosponsored the measure.

"We have to join the rest of the industrialized world and guarantee health care to all, including the undocumented," Sanders declared to cheers last month in Pasadena, at a presidential forum organized by immigrant rights groups.

But senators who have supported Sanders' bill have rarely campaigned on how it would give people who are in the country illegally access to taxpayer-funded health care.

Pressed last month on "State of the Union" to say whether her sponsorship of the bill meant she supported giving Medicare to those "in this country illegally," Harris demurred.

"Let me just be very clear about this. I'm opposed to any policy that would deny in our country any human being from access to public safety, public education, or public health, period," the California Democrat told CNN.

Her answer swiftly prompted outrage from the right.

"It's completely unfair to the millions of Americans who do pay into the system," GOP Chairwoman Ronna McDaniel tweeted later that day in response to Harris' quote.

Asked in early May whether undocumented immigrants should have access to federal benefits, like Medicare and Medicaid, former Vice President Joe Biden sidestepped the question.

"Look, I think that anyone who is in a situation where they're in need of health care, regardless of whether they're documented or undocumented, we have an obligation to see that they're cared for," Biden said.

Notwithstanding his parsing, President Trump's team quickly denounced the former vice president.

"So wrong, Sleepy Joe. We must take care of American citizens and our great seniors first," the campaign retorted.

Undocumented immigrants are explicitly blocked from the Affordable Care Act's marketplace, and extending taxpayer-funded coverage to them has long been a third rail in the American health care debate.

In 2009, while a majority of Americans favored universal health care, 80 percent opposed providing health care to undocumented immigrants. That year, Republican Rep. Joe Wilson infamously shouted "you lie" during then-President Obama's State of the Union remarks, after Obama said his health care proposals would not cover illegal immigrants.

Today an estimated 45 percent of undocumented, "non-elderly" immigrants are uninsured. The Congressional Budget Office this year estimated some 11 million "non-citizens who are not lawfully present" could remain uninsured under a single-payer system, with half of them losing coverage altogether unless they are made eligible for the public plan.

A handful of states already cover undocumented children and pregnant women, including California. And many local governments, Los Angeles County among them, offer free health care to low-income residents regardless of immigration status.

Though California is poised to be the first to offer some low-income undocumented adults coverage statewide, eligibility would be capped at age 25.

"I think Republicans will make it an issue, but states are doing this and ultimately Medicaid, a lot of the time, it's up to states to do it," Jim Kessler, vice president of policy at Third Way, tells CBS News.

"I'm not saying this is going to be broadly popular if you do it. But on health care there are red lines that, if you cross it, you are in a danger zone with average voters. Expanding coverage of health care to some undocumented workers doesn't cross that red line, in my view," Kessler added.

Though a far cry from the single-payer system endorsed by Sanders and others, Kessler said even his center-left think tank's ownhttps://www.thirdway.org/report/cost-caps-and-coverage-for-all-how-to-make-health-care-universally-affordable"cost caps and coverage for all" plan also makes sure to address coverage for uninsured undocumented immigrants.

"I think what we're showing is whether a candidate is talking about Medicare for All like Governor Newsom does, or universal coverage in general, it's important to tie that to specific things we can do in year one," said Wright, of the Health Access coalition.

"There's no conflict between having a broad vision of what universal health care might look like, whether it's Medicare for All' or whatever else it might be, and at the same time here taking tangible, concrete steps to provide help," he added.