Democratic Sen. Cory Booker of New Jersey on Friday announced he's running for president in 2020.

In his first radio interview after announcing his campaign, Booker called for marijuana to be legalized.

Booker has been focusing on marijuana legalization for quite some time as part of his broader calls for criminal-justice reform.

Democratic Sen. Cory Booker kicked off his 2020 campaign on Friday, and he called for the legalization of marijuana in his first radio interview after announcing his candidacy.

Speaking about criminal-justice reform on the Tom Joyner Morning Show, the New Jersey senator said, "It means changing our drug laws. Ending prohibition against marijuana."

Booker highlighted the disproportionate impact of marijuana laws on the black community, and the fact that black people are roughly four times more likely to be arrested for marijuana possession despite having similar rates of usage to whites.

"We do not have equal justice under the law," he said. "I believe in redemption."

"This is a cancer on the soul of our country," Booker said on the subject of mass incarceration as he discussed drug laws in the US. "Too many of our children are being shuttled into cages."

In a separate interview on SiriusXM's Joe Madison Show, Booker echoed his call for unity and concerns about hyper-partisanship that were included in a video released as part of his campaign announcement.

"We've got to get away from reflexive partisanship," Booker said. "We have a common pain in this country, but we've lost that sense of common purpose."

Read more: Sen. Cory Booker announces he's running for president in 2020

In the video Booker released Friday morning, he said, "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."

"It is not a matter of 'Can we?' It’s a matter of do we have the collective will, the American will? I believe we do," Booker added. "Together, we will channel our common pain back into our common purpose. Together, America, we will rise."

When Madison asked Booker to list the three issues he plans to focus on the most, he said, "There's no single issue, one switch to flip, you've got to focus on people's quality of life and all of things that affect them."

Booker then zeroed in on the need for economic and environmental justice, as well as healthcare.

"We are falling short on economic justice. We are falling short on environmental justice," he said.

Booker launched his 2020 campaign on the first day of Black History Month. If he's elected, Booker would be the second black president in US history and the first direct descendant of slaves to occupy the White House.

A former mayor of Newark, New Jersey, Booker has focused heavily on criminal-justice reform throughout his political career.

Booker in 2017 introduced legislation to legalize marijuana at the federal level, highlighting the disproportionate impact that the enforcement of its prohibition has on communities of color.

"For decades, the failed War on Drugs has locked up millions of nonviolent drug offenders — especially for marijuana-related offenses — at an incredible cost of lost human potential, torn apart families and communities, and taxpayer dollars," Booker said at the time. "The effects of the drug war have had a disproportionately devastating impact on Americans of color and the poor."

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At present, recreational marijuana is now legal in 10 states, and medical marijuana is legal in 33. A strong majority of Americans (62%) also favor legalizing marijuana, according to an October 2018 survey from Pew Research Center, so this is an easy issue for Booker to campaign on.

Views on marijuana among the US public have shifted drastically over the past 15 to 20 years. In 2000, for example, just 31% of Americans said they believed marijuana should be legalized.