Booker, who was never able to secure a top-five position in voter-preference surveys, dropped out of the race on Monday ahead of the February 3 Iowa caucuses, the Democrats' first nominating contest, reports Efe news.
His decision comes six weeks after California Senator Kamala Harris ended her White House bid and means that the lone African-American candidate left in the Democratic presidential contest is former Massachusetts Governor Deval Patrick, who got a late start in the race and also is not one of the front-runners in the polls.
African-Americans are a key voting bloc for Democrats in their bid to defeat incumbent President Donald Trump in the November 3 election.
Booker's move came after he failed for the second straight time to qualify for a Democratic debate despite having launched a digital and TV ad campaign valued at around $500,000.
"It's with a full heart that I share this news - I'm suspending my campaign for president," the former Mayor of Newark, New Jersey, wrote on Twitter.
He added in an email to supporters that his campaign has reached a juncture in which he needs more money to gain ground and that those funds are lacking.
That money is "harder to raise because I won't be on the next debate stage and because the urgent business of (Trump's) impeachment (trial in the Senate) will rightly be keeping me in Washington".
Booker did not participate in the last Democratic debate on December 19, 2019 in Los Angeles and also did not qualify for a debate in Des Moines, Iowa, scheduled for Tuesday night.
"It was a difficult decision to make, but I got in this race to win, and I've always said I wouldn't continue if there was no longer a path to victory," the Senator, whose message of community, love and unity failed to resonate with voters, said in the email.
Booker also has repeatedly spoken out about the lack of racial diversity among the candidates remaining in the Democratic field.
The 50-year-old Booker became Newark's mayor in 2006 after making an unsuccessful, underdog bid for that same office four years earlier; that 2002 contest was documented in the critically acclaimed, Oscar-nominated documentary feature "Street Fight," which helped boost the politician's public visibility.
After winning re-election in 2010, Booker ran for the New Jersey Senate seat left vacant following the death of 89-year-old Democrat Frank Lautenberg.
He won that 2013 special election and then was re-elected to the same seat a year later. Booker is up for re-election once again this year in a state where a Republican senator has not been voted into office since 1972.
The race for the Democratic nomination is down to 12 following Booker's exit, with former Vice President Joe Biden, Senators Bernie Sanders and Elizabeth Warren and the former Mayor of South Bend, Indiana, Pete Buttigieg, leading the polls.
After Booker's announcement, Trump took to Twitter to sarcastically mock the failed campaign of one of his harshest critics.
"Really Big Breaking News (Kidding): Booker, who was in zero polling territory, just dropped out of the Democrat Presidential Primary Race. Now I can rest easy tonight. I was sooo concerned that I would someday have to go head to head with him."
( With inputs from IANS )