WASHINGTON (AFP) - Democrat Cory Booker announced on Friday (Feb 1) he is running for US president, bringing a charismatic African-American voice to the crowded nomination race to take on Donald Trump in 2020.

Making the announcement in a video, the senator from New Jersey highlighted his roots in a racially divided urban America and evoked the civil rights movement in describing his own barrier-busting experience.

"Together, we will channel our common pain back into our common purpose. Together, America, we will rise," said Booker, whose career and political appeal echoes that of former president Barack Obama.

Booker joins a crush of Democrats vying to run next year - with eight other declared candidates ranging from Trump nemesis Elizabeth Warren, to Kamala Harris, a barrier-breaking senator from California who aspires to be the nation's first black female president.

The 49-year-old's star rose as the telegenic mayor of Newark, a New Jersey city with a history of racial conflict and urban ills.

In his video, he recalled the racial discrimination his family fought, with the help of white civil rights lawyers, to buy a home in a neighbourhood with good public schools.

"The history of our nation is defined by collective action; by interwoven destinies of slaves and abolitionists; of those born here and those who chose America as home; of those who took up arms to defend our country, and those who linked arms to challenge and change it," he said.

A standout early on, Booker attended Stanford University, studied at Oxford as a Rhodes Scholar, and went to Yale Law School.

But he moved to Newark as a young community activist, at one point staging a 10-day hunger strike to draw attention to problems of housing and urban development.

"I am the only senator who goes home to a low income inner city community, the first community that took a chance on me," he said.

Another distinction: Booker is single, and if elected would be the first unmarried US president since 1884.

As New Jersey's first black US senator he has focused on criminal justice reform, reaching out to likeminded Republicans in an otherwise gridlocked Congress.

KAVANAUGH INTERROGATOR

Booker gained attention as a passionate interrogator of Brett Kavanaugh, Trump's Supreme Court nominee, during high-profile confirmation hearings last September.

With a flair for the dramatic, the senator compared himself to "Spartacus" as he revealed confidential emails referencing Kavanaugh's positions on racial discrimination.

Booker declared he was prepared to lose his Senate seat to make the emails public, but the Senate ethics committee decided not to punish him for the rules violation.

Preferring an upbeat approach to politics, Booker has avoided open conflict with Trump, making no mention of the president in Friday's announcement.

Among his rivals for the White House nomination, Senator Harris likewise made a mark with her tough, prosecutorial questioning of Kavanaugh.

Harris also identifies as African-American, as well as South Asian-American, in a nod to her Jamaican-born father and Indian mother.

Others in a remarkably diverse Democratic field include Senator Warren of Massachusetts; former San Antonio, Texas mayor Julian Castro; Hawaii congresswoman Tulsi Gabbard; and New York Senator Kirsten Gillibrand.

Former vice president Joe Biden also is mulling a run, citing his deep experience as outweighing reservations over his age, 76.

And former Starbucks chief executive officer Howard Shultz, a billionaire one-time Democrat, made waves on Sunday when he said he might run as an independent, potentially positioning himself as a spoiler for Democrats.

The Democratic primaries are still a year away, beginning with the Iowa caucuses, and unlike 2016 when Hillary Clinton dominated the field, there is no clear frontrunner.