Sanders said he was considered "crazy" for proposing this policy three years ago, but numerous Democrats now running for president also support it, though each candidate has a different vision for universal health care.
After falling short in 2016 against Hillary Clinton, Sanders told supporters at a rally at Brooklyn College, which he once attended, that his campaign is saying "loudly and clearly that the underlying principles of our government will not be greed, hatred and lies". But you know what I'm doing? Those areas have never been issues for me.
"We are not only going to defeat (President Donald) Trump, we are going to transform the United States of America".
"Climate change is making extreme weather events, including tornadoes, worse", claimed the Vermont independent in a Facebook post on Monday, which linked to an EcoWatch article about the Lee County twister.
"I am not going to tell you that I grew up in a home of desperate poverty", Sanders said to a crowd of roughly 13,000 people.
In a bid to win over black voters, Sanders noted that the U.S. still had a long way to go to end institutional racism and income disparities in a country where the average black family has one-10th the wealth of the average white family.
"Well, I think you need this one", Sanders said with a laugh.
Sanders, 77, described living in Flatbush, not far from Brooklyn where he shared a 3 1/2-room, rent-controlled apartment with his parents and brother.
One of his newest campaign hires, deputy national press secretary Belén Sisa, won't even be able to vote for Sanders in 2020 because she is a self-admitted illegal immigrant.
Sanders was narrowly defeated in IL by Hillary Clinton during the March 2016 primary.
All clear: Tornado warnings, watch canceled in Lee County
The National Weather Service confirmed a tornado by radar that toppled trees in Walton County, Florida, located in the Panhandle. He said the threat of more tornadoes would continue for several hours as the storm system headed toward the Atlantic seaboard.
He had begun his 2016 campaign in Vermont, which he has represented in the Senate for almost two decades. After that, Sanders heads to Chicago for a Sunday nightrally at Navy Pier. Democrats have been mobilized by the election of Trump and are seeking a standard-bearer who can oust him from office.
Sanders is aiming to connect his working-class childhood to his populist political views that have reshaped the Democratic Party.
But Sanders is part of a very crowded and diverse field of opponents - many of whom are decades younger than him. "I think if you look at my record in terms of civil rights and other areas you will find that it is consistently a very very strong record".
Chicago resident Christopher Valentin said he is supporting Sanders because the senator from Vermont can connect to people of all political backgrounds.
"The way I see it, I've got plenty to talk about as it is - about the structural change we need in this country and laying out how we can do this".
But for his second White House run, he's trying to showcase more of his personal story.
The burgeoning narrative of humble beginnings and early civil rights activism preceded Sanders' speech when three speakers took to the stage, including, the Rev. Rep. Terry Alexander, State Sen.
Sanders said he became involved at that time with the Congress on Racial Equality, or CORE, and helped fight segregated housing at the University of Chicago.
"The Democratic Party has adopted so much of his platform, so he won the moral argument in 2016", Turner said.