Washington (CNN) New Jersey Sen. Cory Booker said Friday he was "taken aback" by former New York City Mayor Michael Bloomberg calling him "well-spoken," and said Bloomberg played into a tired trope about African Americans.

"It's sort of stunning at times that we are still revisiting these sort of tired, you know, tropes or the language we have out there that folks I don't think understand. And the fact that they don't understand is problematic," the 2020 presidential candidate told Signal Boost on SiriusXM

In an interview that aired Friday morning, Bloomberg told CBS This Morning , "Cory Booker endorsed me a number of times. And I endorsed Cory Booker a number of times. He's very well-spoken. He's got some good ideas. It would be better the more diverse any group is." The billionaire, another 2020 contender, was responding to a question about how, so far, this month's Democratic primary debate is expected to feature only white candidates.

The comments come as Booker and former HUD Secretary Julián Castro decry the lack of diversity atop the Democratic field after California Sen. Kamala Harris, the only black woman in the 2020 race, ended her presidential campaign.

Booker said he hopes Bloomberg "gets it now" and that people around him are talking to him about why that language is problematic. He said he has known Bloomberg for a long time and that he has a "great deal of regard" for his fellow candidate.

"I hope people around (Bloomberg) are talking to him about why that plays into what is for the black community in particular, just these are signs of frustration that we continue to deal with issues, whether it was the black face controversies from earlier this year, to the challenges that I don't think folks understand with Kamala dropping out of the race," Booker said.

Later Friday, when asked about his comments, Bloomberg noted that he "probably shouldn't have used the word."

Before becoming a senator, Booker was mayor of Newark, New Jersey, from 2006 to 2013. Bloomberg was mayor of neighboring New York City for several overlapping years, from 2002 to 2013.

Booker said many of his friends and family who weren't even supporting Harris for president "found it just insulting that she would not be in this race with her qualifications, with her experience, with her talent, with her gifts, and other people are, who frankly, very bluntly, do not have her same record."

He said the Democratic Party needs to understand that the Democratic nominee can't win without "not just the African American vote, but we can't win without the enthusiastic support of black voters, and we saw that between 2016 and 2012."

Booker has hit the fundraising threshold for the next debate, but still needs to cross the polling threshold to get on the debate stage later this month.





, Bloomberg falsely claimed that "nobody asked" him about the controversial stop and frisk policing tactic until he started running for president, despite him being asked about and defending the policy as recently as earlier this year. Stop and frisk is a type of aggressive policing that allowed -- some say encouraged -- officers to detain a person on virtually any type of vague suspicion, search that individual without a warrant and arrest the person if any kind of illegal substance or weapon was found. Critics say the measure is racist because it overwhelmingly impacts men of color. In 2007, former Vice President Joe Biden drew scrutiny for a similar comment he made about then-Sen. Barack Obama, who was his rival in the presidential race at the time. "I mean, you got the first mainstream African American who is articulate and bright and clean and a nice-looking guy," Biden said. "I mean, that's a storybook, man." Biden later said his comments were taken out of context and that he regretted any offense they may have caused. In the same interview with CBS , Bloomberg falsely claimed that "nobody asked" him about the controversial stop and frisk policing tactic until he started running for president, despite him being asked about and defending the policy as recently as earlier this year. Stop and frisk is a type of aggressive policing that allowed -- some say encouraged -- officers to detain a person on virtually any type of vague suspicion, search that individual without a warrant and arrest the person if any kind of illegal substance or weapon was found. Critics say the measure is racist because it overwhelmingly impacts men of color.

The radio show Booker appeared on is hosted by Zerlina Maxwell and Jess McIntosh -- McIntosh is a CNN contributor.