New Jersey Sen. Cory Booker, the former mayor of Newark, on Friday said he will seek the Democratic nomination for president with a sweeping call to unite the nation around a “common purpose.”

The 49-year-old Democrat, the second black candidate in a primary field that’s already historically diverse, made his announcement in an email and video on the first day of Black History Month.

“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,” Booker said in his video.

“I believe that we can build a country where no one is forgotten, no one is left behind; where parents can put food on the table; where there are good-paying jobs with good benefits in every neighborhood; where our criminal justice system keeps us safe, instead of shuffling more children into cages and coffins; where we see the faces of our leaders on television and feel pride, not shame,” he said.

“It is not a matter of can we, it’s a matter of do we have the collective will, the American will?” Booker added in the video, which shows him strolling through his Newark neighborhood. “I believe we do.”

He enters a crowded presidential primary, with three of his fellow Democratic senators — Kirsten Gillibrand of New York, Elizabeth Warren of Massachusetts and Kamala Harris of California— already either declared or exploring a run.

Booker’s campaign manager will be Addisu Demissie, a veteran of his 2013 Senate race, who most recently ran Gavin Newsom’s successful bid for California governor, according to CNN. Demissie also served as a field organizer for John Kerry’s 2004 caucus campaign, returning in the 2008 cycle on behalf of Hillary Clinton.

Booker’s decision to throw his hat in the rapidly widening ring came as no surprise after spending months teasing his intentions.

To build connections with key powerbrokers, he visited the early-voting states of Iowa, New Hampshire and South Carolina.

Booker won a special Senate election in 2013 to replace Democrat Frank Lautenberg and then won a full Senate term in 2014.

Thanks to a law that New Jersey’s governor signed in November, Booker will be able to run for a second full term in 2020 while mounting his bid for the White House.

But several of Booker’s rival presidential hopefuls bring higher name recognition to a race that also may feature popular former Vice President Joe Biden.

He also will likely stand alone as an unmarried candidate, though he brings a compelling background that could help elevate his message of bringing Americans together around what he described as “common purpose.”

Booker’s father grew up in a low-income community in North Carolina, and the senator has recalled his family’s struggle to settle in suburban New Jersey amid discrimination against black homebuyers.

“When I was a baby, my parents tried to move us into a neighborhood with great public schools, but Realtors wouldn’t sell us a home because of the color of our skin,” he said in his video.

“A group of white lawyers, who had watched the courage of civil rights activists, were inspired to help black families in their own community, including mine. And they changed the course of my entire life. Because in America, courage is contagious.

“My Dad told me, ‘Boy, never forget where you came from, or how many people had to sacrifice to get you where you are.’ ”

Booker, a gifted orator and Yale Law School grad, has brought a passionate style to his Senate achievements — at times fusing his personal spirituality with policy proposals aimed at promoting social justice.

He played a key role in the bipartisan criminal justice reform bill that President Trump supported last year, for example, a deal he helped strike after jousting with Republicans during the battle over Supreme Court Justice Brett Kavanaugh’s confirmation.

While Booker has been reluctant to attack Trump directly, the president took at a shot at the senator during a White House event in October, saying he “ran Newark, New Jersey, into the ground.”