New York City will begin guaranteeing comprehensive health care to every single resident regardless of someone's ability to pay or immigration status, an unprecedented plan that will protect the more than half-a-million New Yorkers currently using the ER as a primary provider, Mayor Bill de Blasio said. 

It's not health insurance, his spokesman clarified after the surprise announcement on MSNBC Tuesday morning.

"This is the city paying for direct comprehensive care (not just ERs) for people who can't afford it, or can't get comprehensive Medicaid -- including 300,000 undocumented New Yorkers," spokesman Eric Phillips tweeted.

De Blasio said the plan will provide primary and specialty care, from pediatrics to OBGYN, geriatric, mental health and other services, to the city's roughly 600,000 uninsured. He said the city already has the foundation for such a plan -- a public health insurance option that helps get direct care to undocumented residents. 

That option will be expanded, the mayor said, and supported with the addition of a new program called NYC Care. That plan will roll out in 2019 and build out over the next few years, de Blasio said. It'll cost about $100 million, Politico said.

New Yorkers will be able to access the program through the city's website or simply by calling 311. There will be no tax hikes to fund it, the mayor said. 

"We'll put the money in to make it work; it's going to save us money down the line," de Blasio said on MSNBC. "We're already paying an exorbitant amount to pay for health care the wrong way when what we should be doing is helping them get the primary care."