Sen. Cory Booker took dead aim at Joe Biden at the NAACP conference in Detroit on Wednesday, saying the former vice president was an "architect of mass incarceration" who pushed legislation that "destroyed communities."

Booker was replying to a question from CBS News' Caitlin Huey-Burns, who asked the New Jersey Democrat about Biden's new criminal justice plan. Biden says his new plan addresses some of the problems with the 1994 crime bill he championed and that progressive activists frequently criticize.

Booker, however, was unimpressed with Biden's evolution on the issue.

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"I'm disappointed that it's taken Joe Biden years and years until he was running for president to actually say he made a mistake, that there are things in that bill that were extraordinarily bad. I've been living and working now in Newark, New Jersey for 20 years and we've seen the devastating impact of legislation like that that has destroyed communities, that has put mass incarceration on steroids. And so I'm disappointed it's taken him so long to own up to that, and now he's unveiled his crime bill," Booker said.

"For a guy who helped to be an architect of mass incarceration, this is an inadequate solution to what is a raging crisis in our country. We have 5 percent of the globe's population but we have 25 percent of the globe's prison population. We have the over-incarceration of low -ncome folks — veteran folks, addicted folks, mentally ill folks, and disproportionately black and brown folks. And so for him not to have a more comprehensive, bold plan to deal with this is unacceptable to me, especially because he is partly responsible for the crisis we have now."

Biden later fired back, telling Huey-Burns that Newark allowed police officers to "stop and frisk" when Booker was mayor — until the Obama administration put a stop to it.

"Cory knows that's not true, number one. Number two, you know, the significant part of incarceration, it occurred before the crime bill was written. Number two, if you look at the mayor's record in Newark, one of the provisions I wrote in the crime bill, a pattern of practice and misbehavior, his police department was stopping and frisking people -- mostly African American men. We took action against them, the Department of Justice took action. Held the police department accountable," Biden said.

"[Booker] objected to federal interference. If he wants to go back and talk about records, I'm happy to do that. But I'd rather talk about the future. I introduced a crime bill that I challenge him or anyone else to tell me how he has a better plan than I have for moving from here. And you know, it's about the future. What do we do from this point on? What do we do about the incarceration that occurs?"

When Biden released his criminal justice reform plan on Tuesday, Booker tweeted, "You created this system. We'll dismantle it." The tweet, which, though widely seen as a shot at Biden, did not reference him by name.

It’s not enough to tell us what you’re going to do for our communities, show us what you’ve done for the last 40 years. You created this system. We’ll dismantle it. — Cory Booker (@CoryBooker) July 23, 2019

Still, Booker has recently been more pointed in his criticism of Biden. When asked about the crime bill in May, Booker was more conciliatory, saying that while the legislation itself was "awful" he still had a high opinion of Biden.

"Look, I sincerely – and I use this word – I sincerely love Joe Biden," Booker told HuffPost at the time.

But he hated the crime bill. Booker said, "From the time I was in law school to the time I was mayor in the city of Newark, we were building a new prison or jail every 10 days in America, while the rest of our infrastructure crumbled, overwhelmingly putting people in prison for nonviolent drug offenses that members of Congress and Senate admit to breaking drug laws now.

"So that bill was awful. We should all agree with a chorus of conviction. That bill was a mistake. Good people signed onto that bill. People make mistakes, but let's all conclude that that crime bill was shameful. What it did to communities like black and brown communities like mine, low-income communities from Appalachia to rural Iowa. It was a bad bill."

Biden and Booker may have a chance to have a more direct conversation about criminal justice when they appear side by side at next week's Democratic presidential debate.