For conservatives, much of the response was comedic and dismissive, with some referring to Warren as "Pocahontas" - the nickname US President Donald Trump uses for the senator due to her claims of Native American ancestry. While she called out the "bloated" USA defense budget in a recent speech and called for cuts, she did not vote against Trump's massive increases in military spending when she had the chance. "How did we get here?"
In a four-and-a-half minute video, Warren makes clear some of the very themes that catapulted her to national prominence will define her upcoming presidential run: economic equality, government accountability and reining in big corporations. She is hoping her reputation as a populist fighter can help her navigate a Democratic field that could include almost two dozen candidates.
"Warren missed her moment in 2016, and there's reason to be skeptical of her prospective candidacy in 2020", the Boston Globe wrote in a scathing editorial in December. Bernie Sanders and rising star Beto O'Rourke, the departing Texas congressman who just lost a bid for the US Senate.
Warren has often described spending her Oklahoma upbringing "on the ragged edge of the middle class".
Warren, who said she was creating an exploratory committee that will allow her to raise funds and hire staffers, will be among a crowded field of Democrats taking a shot at the White House.
Warren appears to target voters of varied cultural, geographic and economic backgrounds with an anti-corporate, pro-worker message in her initial campaign pitch.
She was married at 19, pregnant at 21 and a Rutgers School of Law graduate by 26.
Warren has spent most of her adult life in academia, doing groundbreaking research on consumer bankruptcy.
Warren was an academic and consumer advocate who gained notoriety during the 2008 financial crisis when she chaired a congressional panel to oversee the bank bailout. She ran for Senate in 2012, and beat incumbent Scott Brown. "That's ok by me", Warren's email reads. "I was a Republican at a time when I felt like there was a problem that the markets were under a lot more strain".
While some Democratic operatives questioned the wisdom of making a major announcement during the New Year holiday, when fewer Americans may be watching the news, the source familiar with Warren's thinking said her primary concern was getting an early start on campaign activities.