Cory Booker wants to be president, and the New Jersey senator has launched a markedly optimistic bid to challenge Donald Trump in what is one of the most politically divided moments in modern US history.

Mr Booker launched his bid for the presidency on Friday, placing his African American heritage at the centre of a campaign built on a message of unity.

“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,” Mr Booker says in a video released to announce his campaign, which launched on the first day of black history month.

In the video, Mr Booker is seen walking through his Newark neighborhood, where he served as mayor for seven years before winning his senate seat in 2013.

“I'm Cory Booker and I'm running for president of the United States of America”, he continues.

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Mr Booker has joined what is expected to become a massive field of candidates vying for the Democratic nomination for president. He is the second African American candidate to join the race, after California senator Kamala Harris joined last month.

Other candidates include former housing and urban development secretary Julian Castro, New York senator Kirsten Gillibrand, and Massachusetts senator Elizabeth Warren, among others.

Some of the biggest names that have been talked about in the past year have so far refrained from officially joining the race, or from indicating concrete plans to run.

Those candidates include former vice-president Joe Biden and Vermont senator Bernie Sanders. Both men would enter the race with significant backing and name recognition, and would likely be seen as immediate frontrunners.

Mr Booker said in his announcement video he is “the only senator who goes home to a low-income, inner city community”, and that Newark was ”the first community that took a chance on me”.

The 49-year-old has pledged to refuse support from Super PACs during his campaign, which are independent political spending organisations that are allowed to raise unlimited amount of cash from donors, but cannot explicitly coordinate with campaigns.

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Mr Booker has supported “Medicare-for-all” as a senator and has been lauded for his progressive positions on race and immigration. Last year, he took the rare step of openly opposing former senator Jeff Sessions' nomination as atttorney general based on his alleged history of racial discrimination.

He has also received praise for his role in the confirmation hearings of Supreme Court justice Brett Kavanaugh, who had been accused by multiple women of sexual misconduct when he was a teenager and in college.

During those proceedings, a column Mr Booker wrote while a student at Stanford was surfaced by conservative outlets in which he admitted to groping a woman at a party.

While those outlets attempted to smear the senator for the “revelation”, the documents resulted in highlighting Mr Booker’s past comments about recognising female autonomy, and his stances against sexual harassment.

He is likely to face questions for some of his more contentious votes in the US Senate, including a 2017 vote in which he sided with Republicans to kill a bill aimed at reducing prescription drug prices by allowing Americans to buy them from Canada.