Elizabeth Warren has fired the starting gun for the 2020 race for the White House, becoming the most high-profile Democrat to take the first step towards a presidential campaign.
Ms Warren, 69, a progressive Democrat who has exchanged stinging insults with President Donald Trump, said on New Year’s Eve that she has formed an exploratory committee to run for president in 2020.
In a video, released on her website, she set out her vision for the country.
"Most of us want the same thing, to be able to work hard, play by the same set of rules and take care of the people we love," she said.
The Massachusetts senator, born in Oklahoma and known as a liberal firebrand in her party, emphasised opportunity for all Americans, not just the wealthy.
In the video she discussed her working class family’s struggle in Oklahoma to ensure her success, after her father had a heart attack and couldn’t work, and her mother took a minimum wage job at Sears.
"I’ve spent my career getting to the bottom of why America’s promise works for some families, but others who work just as hard slip through the cracks and into disaster."
She said the middle class was "under attack", highlighting the "broken system" of billionaires, big corporations, and Wall Street finance.
"Today, corruption is poisoning our democracy," she said, attacking the health insurance firms, big banks and oil companies.
She didn’t mention Mr Trump by name – although she included a clip of his chanting "Build that wall", as she criticised politicians who seek to divide America.
On a Twitter post, she added: "That’s what I’m fighting for, & that’s why I’m launching an exploratory committee for president. I need you with me."
She added: "I’m going to build a grass roots campaign. Together, we’re going to make change.
"Right now, Washington works great for the wealthy and well connected. It’s just not working for anyone else.
"I’m in this fight because I understand what’s happening to working families. I grew up in a paycheque-to-paycheque family. I run for office because I’m grateful down to my toes for the opportunities given to me.
"When we fight for something positive, something big, when we show what Democrats will make happen – that’s how we win."
Her candidacy had been long expected.
Ms Warren said in September she would take a "hard look" at running for the Democratic nomination to challenge Mr Trump in 2020.
She and Mr Trump clashed frequently through the 2016 presidential campaign and Mr Trump has cast aspersions on her claim to Native American ancestry, referring to her as "Pocahontas."
Ms Warren, an architect of the Consumer Financial Protection Bureau set up after the 2008 financial crisis, has been a strong voice in the US Senate on financial issues.
A former Harvard Law School professor, she campaigned with Democratic presidential candidate Hillary Clinton in 2016 and attacked Mr Trump as an “insecure money grubber” driven by greed and hate.
She had two children with Jim Warren, Amelia and Alexander, before divorcing him in 1978.
Since 1980 she has been married to Bruce Mann, a professor of law at Harvard.