Charlamagne, a black comedian and author who hosts radio programme The Breakfast Club, is known for his blunt interviews of celebrities.
Although he is a Harris supporter, he has been critical of her and President Joe Biden in the past and called Democrats "cowards" for ineffectively prosecuting a case against Republican presidential candidate Donald Trump.
One of his first questions in Detroit was asking Harris to address a common rumour - that she disproportionately locked up black men over her more than a dozen years as San Francisco's district attorney.
Harris said she was "one of the most progressive prosecutors" on marijuana cases, and would work to decriminalise it, because she knows how that has hurt certain populations, especially black men.
Charlamagne's interview with Harris started broadcast on iHeartRadio at 5pm on Tuesday (local time).
On Wednesday, Harris will be interviewed on Fox News, the conservative-leaning network which paid a $US787 million ($NZ1.29 billion) settlement in 2023 to a voting machine company that sued it over false claims by some Fox hosts of vote-rigging in the 2020 presidential election.
She is also weighing joining the podcaster Joe Rogan, whose show reaches millions of men across the political spectrum, and who has joked that a "puppet master" was behind Harris' strong debate performance against Trump.
The effort reflects increasing anxiety within Democratic circles about Harris' waning momentum in the handful of decisive election states and fears that her under-performance with men, and black men in particular, could doom her bid for the White House.
Harris' lead over Trump has narrowed in recent days, several polls show. Her lead held steady at 3 points in the latest national Reuters/Ipsos poll and other battleground state polls show the two in a dead heat.
Harris has been on a media blitz in recent days, speaking with friendly hosts from comedy shows, talk shows and podcasts.
During her fifth trip to the Detroit area since launching her campaign in July, Harris will also promote a set of recently unveiled policy proposals aimed at black men, including forgivable small business loans and access to a new legal recreational marijuana industry. She is visiting with a black -owned small business.
The Harris campaign and Democrats - including former President Barack Obama - have expressed deep concern about whether black men will turn out on November 5 in numbers seen in past elections and whether they will support Harris or Trump.
If elected, Harris would be the second black president and first black woman in the office.
Over a quarter of young black men say they would support Trump in the election race, according to a September poll by the NAACP, the nation's largest civil rights organisation.
Biden received about 80% of the black male vote in 2020.
