He becomes the fourth U.S. Senator in the Democratic primary and the second African-American candidate in a race that is expected to be highly competitive, without a singular commanding front-runner.
The second-term senator from New Jersey had appeared at political events in Iowa and New Hampshire as speculation mounted that he would parlay the Kavanaugh fracas into a presidential run. In addition to Harris, D-Calif., Booker joins Sens.
The 49-year-old Booker, a former Newark mayor who was first elected to the Senate in a 2013 special election, has always been seen as a likely candidate to challenge Trump.
Booker was reportedly on the short-list of potential vice presidential candidates drawn up by Democratic nominee Hillary Clinton in 2016.
Booker's video announcement released Friday is classic Booker: brimming with hope, compassion, optimism. Cory Booker (D-N.J.) is sexist for adding his name to the growing list of Democrats running for president in 2020, some of whom are women.
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.
Booker was a strong proponent of the criminal justice reform bill passed by Congress in December and backed by the White House.
The affable Booker, known for his fluency in connecting with voters during an age of selfies and social media, also could face some difficulty winning the hearts of the Democratic base due to his past financial ties to banking and pharmaceutical interests. McCain interjected by saying that SNL parodies tend to become a reality, emphasizing their parody of her father's former 2008 presidential running mate Sarah Palin: "there's a power in that as well".
While Obama was raised by a single white mother who frequently struggled to make ends meet, Booker's parents were among the first black executives at computer giant IBM.
In some ways, Booker is a political heir to former President Jimmy Carter, who in the aftermath of the Nixon administration pledged a government "as good and honest and decent and compassionate and filled with love as are the American people". In 2017, he co-sponsored Bernie Sanders' Medicare-for-All bill. What's your objection to Kamala Harris running, Elizabeth Warren, Kirsten Gillibrand, these others that are already announced?
At times, Mr Booker has caught Mr Trump's attention.
"He's a person who operates between instincts, gut and faith", said Rep. Cedric Richmond, a Louisiana Democrat who's the most recent former chairman of the Congressional Black Caucus.
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". "But I think the reward is higher, because that means more if you can inspire, versus anger", Sterzenbach said. I really do think we're at a moral moment in our country.