He predicted he would win the nomination in a field of now-double digit rivals and then defeat President Donald Trump, "the most dangerous president in modern American history."
After falling short in 2016 against Hillary Clinton, the Vermont independent 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. It will not be racism, sexism, xenophobia, homophobia and religious bigotry. That is going to end."
Sanders pledged to fight for "economic justice, social justice, racial justice and environmental justice."
He had begun his 2016 campaign in Vermont, which he has represented in the Senate for nearly two decades. But this time, as he tries to showcase more of his personal story, Sanders kicked off his 2020 bid in the New York City borough where he grew up as the son of a Jewish immigrant and lived in a rent-controlled apartment.
Campaign priorities include "Medicare for all," a $15-an-hour minimum wage and addressing climate change. And Sanders is focusing on his working-class roots and how his family's financial struggles have shaped his views. In those reflections is an implicit contrast to another New Yorker, Trump, a billionaire who hails from Queens.
After Brooklyn, Sanders planned to travel to Selma, Alabama, where he will be among the politicians commemorating the anniversary of the 1965 clash known as "Bloody Sunday," when peaceful demonstrators were beaten back by Alabama state troopers as they attempted to cross the Edmund Pettus Bridge. A second campaign rally this weekend was set for Chicago, where he attended the University of Chicago and was involved in civil rights protests.
Sanders had previously frustrated some aides and supporters with his reticence to share more of his personal story.
Sanders joins the 2020 race not as an outlier but as one of the best-known candidates in an large and expanding field. He also has a strong base of small-dollar donors: In the first week of his campaign, Sanders raised $10 million, far outpacing his rivals.
The political moment that he faces in his second bid, however, is far different than when he ran four years ago. A number of the liberal positions that Sanders has championed, in some cases for years, have been backed by other Democrats in the field, notably Massachusetts Sen. Elizabeth Warren, who is campaigning with similar populist notes.