The future of the Affordable Care Act and comprehensive health care coverage remains uncertain nationally. Republicans have made multiple attempts to repeal all or part of the law, and President Trump cut the advertising budget for the last open-enrollment period, although enrollment numbers were still higher than expected, as PBS reported in December. Amid these conflicting events, some states and cities have taken matters into their own hands, expanding Medicaid coverage, or, as California Gov. Gavin Newsom announced Monday on his first day in office, unveiling plans to expand health care for undocumented immigrants and give California the power to negotiate drug prices.

New York City Mayor Bill de Blasio, however, may have the most ambitious and wide-ranging plan to offer residents medical care. In a move that NBC New York called “historic,” de Blasio announced on MSNBC’s “Morning Joe” on Tuesday that the city will spend $100 million to provide comprehensive health care to both undocumented immigrants and any low-income New Yorkers who don’t have health insurance.

The New York Times suggests that making his announcement on national television may reflect de Blasio’s desire to position himself beyond New York, “as a progressive leader on issues like health care and as a bulwark against the policies of President Trump, particularly on immigration.”

His plan, called NYC Care, is aimed at better addressing the medical needs of low-income New Yorkers who use hospital emergency rooms as their primary source of health care.

During a press conference following his announcement, de Blasio told reporters that his plan will provide access to pediatric, geriatric, OBGYN, mental health and other services to the city’s roughly 600,000 uninsured.

According to NBC New York, de Blasio said that “patients who seek health coverage through NYC Care will receive a card that allows them to see a primary care doctor and seek specialty care services.”

He explained that residents will be able to access services through the city’s website or 311 phone line. Depending on income, residents will either pay for services on a sliding scale, or receive care at no charge.

The Times reports that the mayor’s office emphasizes that de Blasio’s plan “would not be a substitute for any universal health care at the state level or a national single-payer plan.” It’s also not entirely insurance, but a mix of insurance, direct spending for care and, as the Times notes, an extension of MetroPlus, an existing insurance program run by city hospitals that already covers over 500,000 New Yorkers. De Blasio’s new plan aims to expand that number and reach people who might not know they’re qualified.

The Times points out that the city’s hospitals remain under “severe financial strain,” noting that “the current financial plan for city hospitals projects budget shortfalls of over $156 million in 2018, increasing to $1.8 billion in 2022, according to the city’s Independent Budget Office.”

De Blasio, however, remains optimistic, telling MSNBC, “This has never been done in the country in a comprehensive way. … Health care isn’t just a right in theory, it must be a right in practice. And we’re doing that here in this city.”

The program is expected to launch in the Bronx this summer and expand to the city’s four other boroughs through 2021.