New York Democratic Senator Kirsten Gillibrand has announced her plans for a 2020 presidential run during an appearance on late-night television.
She told CBS host Stephen Colbert she has launched an exploratory committee for her bid on Tuesday.
Mrs Gillibrand, a vocal supporter of the #MeToo movement, has made headlines for her sharp criticism of President Trump.
She joins a growing group of Democrats hoping to win the party’s nomination.
“I’m filing an exploratory committee for president of the United States tonight!” she said in a clip of her taped interview released ahead of the programme on Tuesday night.
Asked why she is running, Mrs Gillibrand replied: “As a young mom I’m going to fight for other people’s kids as hard as I fight for my own, which is why I believe health care is a right and not a privilege.”
Registering an exploratory committee with the Federal Election Commission allows Mrs Gillibrand to raise money like a presidential candidate before officially launching her bid.
Who is Kirsten Gillibrand?
Mrs Gillibrand, 52, was appointed to her seat in 2009, when Hillary Clinton accepted the role of US Secretary of State under former president Barack Obama.
Since then, she has won her re-election bids easily and remains popular in New York.
Mrs Gillibrand has one of the largest financial pools to draw from of possible 2020 candidates, with around $10m (£7.7m) in her campaign pocket following her re-election last year.
She is expected to set up her headquarters in Troy, New York, where she lives with her husband and two sons.
The established Democrat reportedly has key staffers on board and released a campaign ad on Tuesday night.
Mrs Gillibrand has been an outspoken supporter for the #MeToo movement as well as fighting sexual assaults on college campuses and in the military.
She has also been a vocal critic of President Donald Trump.
Mrs Gillibrand demanded President Trump’s departure over sexual misconduct allegations in 2017.
Mr Trump responded by claiming Mrs Gillibrand had come “begging” to him for donations and “would do anything” for cash.
As Democrats decried the language as sexist, the White House said the president was only referring to political corruption.
Young, charismatic, and a real contender
Analysis by Anthony Zurcher, BBC Washington
Announcing a presidential campaign on the Stephen Colbert Show may end up a cliché by the time the year is over, but credit Kirsten Gillibrand with being one of the first to try it.
The New York senator’s decision to (almost) thrown her hat into the ring isn’t a huge shock.
She’s long been positioning herself as one of the candidates most likely to capitalise on the #MeToo movement, and her pitch as someone who will “fight as hard for other people’s kids as she would for her own” just might resonate.
Her steady march to 2020 hit a few bumps along the way, however. She angered some Democrats by quickly calling for Senator Al Franken’s resignation after he faced sexual harassment charges. And she alienated Clinton loyalists by criticising Bill Clinton’s handling of the Monica Lewinsky scandal.
These decisions could hurt her, even if she cites them as evidence that she matches her feminist rhetoric with action.
As a New Yorker, however, she can tap into a deep vein of campaign cash. She’s young and charismatic. If she catches the wave of women voters that powered Democrats to victory last year, it just might carry her to the nomination.
Who else is running?
Senator Elizabeth Warren announced her own bid on New Year’s Eve. Democratic representatives Tulsi Gabbard and John Delaney have also announces plans to run.
Senators Kamala Harris, Cory Booker, and Amy Klobuchar have also publically confirmed they are considering a bid.