Democrat Cory Booker says he will run for president in the 2020 election, joining a crowded field of candidates seeking the party’s nomination.
The New Jersey senator, 49, was elected in 2013 after serving as mayor of the state’s largest city, Newark.
He has been a vocal critic of President Donald Trump, slamming his administration’s policies on issues such as immigration and climate change.
Mr Booker has long been touted as a rising star of the Democratic Party.
But he will face tough competition in the party’s primary, with a number of hotly-tipped candidates having already announced their intentions to run.
Kamala Harris, Elizabeth Warren, Kirsten Gillibrand, Tulsi Gabbard and Julian Castro will all contest the Democratic nomination.
It is the first time that more than one woman has competed for the party’s candidacy.
Who is Cory Booker?
The first black senator from New Jersey, Mr Booker grew up in Harrington Park, a mainly white, suburban town in the state.
He played for his high school football team before going on to attend a number of top universities, including Stanford, Oxford and eventually Yale Law School.
After graduating, he moved to Newark to set up a non-profit organisation providing legal aid to poor families in difficult circumstances.
In the run up to his 2006 landslide election as mayor, he lived in a notorious housing project in the city and featured in a film that documented his campaign as a young, black, politician.
He was elected to Congress in 2013 by a significant margin, and became the second black member of the Senate at the time.
As a bachelor, Senator Booker has often faced questions about his sexuality from political opponents and journalists.
Last year, when asked about the speculation on the subject, he told the Philadelphia Inquirer that he is heterosexual.
“Every candidate should run on their authentic self, tell their truth, and more importantly, or most importantly, talk about their vision for the country,” he said.
If elected, Mr Booker would become the first unmarried president since Grover Cleveland was elected in 1885.
He also regularly posts about his vegan diet and his exercise routine on social media.
What does he stand for?
Mr Booker has called for reform of the criminal justice system, affordable healthcare and the legalisation of marijuana.
He is a progressive on social issues, supporting gun control, same-sex marriage, and he has previously tabled a bill that would outlaw “gay cure” therapy.
In a recent speech in Iowa, he spoke about gender equality and criticised President Trump’s record on women’s rights.
“We’re not defined by a president who does not believe women,” he said. “We’re going to be defined when this state not only says that we believe women, but we elect women.”
But progressives have been sceptical about him because of his close ties to Wall Street financial interests, the BBC’s Anthony Zurcher says.
Mr Booker released classified documents relating to President Trump’s Supreme Court nominee Brett Kavanaugh last year and vehemently opposed his nomination, stating that supporters were “complicit in evil”.
His progressive views – and open criticism of the president on social media – has not gone unnoticed.
At a rally last October, Mr Trump said Mr Booker “did one of the worst jobs of any mayor” and “destroyed what he did, he was so bad”.
The president has also targeted him on Twitter, posting in 2016: “If Cory Booker is the future of the Democratic Party, they have no future!”
Last year, the senator was among those targeted in a mail-bombing campaign that was aimed at critics of Mr Trump.
A suspicious item addressed to him was found at a mail facility in Florida.