There’s no let-up from Sen. Cory Booker as he takes aim at Democratic presidential rival Joe Biden over Biden’s role in crafting the landmark 1994 crime bill.

That legislation has been blamed by Booker and many other Democrats for contributing to the mass incarceration of black people in the United States.

One day after slamming the former vice president for being “the proud architect of a failed system," Booker fired away again – this time in Detroit on Wednesday - where he and Biden were among ten White House contenders to address the annual NAACP convention.

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Speaking with reporters after he left the stage, the senator from New Jersey and former Newark mayor argued that the crime bill “put mass incarceration on steroids and so I'm disappointed that it's taken him so long to own up to that.”

Biden once again defended his efforts in drafting the legislation, telling the audience at the convention that in the early 1990s “we had a gigantic epidemic in America of violence, particularly in African-American communities.”

The former vice president also highlighted that the bill had majority support of black members of Congress and mayors.

For a second straight day he highlighted his new, wide-ranging plan to reduce the country’s prison population, reform the nation’s criminal justice system and eliminate racial and income disparities in sentencing.

And Biden - for the first time - pushed back at Booker's claim he was the mass incarcerations "architect," telling reporters, "Cory knows that's not true."

The former vice president took aim at his rival's record - criticizing the stopping and frisking of African-American men by Newark police during Booker's tenure as the city's mayor.

And Biden's campaign went a step further, characterizing Booker's attacks as absurd.

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As a senator from Delaware, Biden helped craft the 1994 bill that was signed into law by then-President Bill Clinton. Biden has long highlighted his role in helping write the law, which at the time was the largest anti-crime bill in the nation’s history. The measure provided for thousands of new police officers, millions of dollars to fund prevention programs, and billions of dollars to build new prisons.

But the law has long been criticized by Democrats, who blame the measure for spiking incarcerations, particularly among minorities, due to a mandatory life sentence policy for repeat offenders.

Biden’s new criminal justice plan, in fact, would reverse the stricter sentence terms for crack versus powder cocaine that were implemented by the 1994 law.

Booker criticized Biden’s plan just a couple of hours after the former vice president unveiled the proposal on Tuesday morning. And he didn’t let up on Wednesday.

“I'm disappointed that it's taken Joe Biden years and years to actually say that he made a mistake, that there were things in that bill that were extraordinarily bad," he said. "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.”

“Now he's unveiled his crime bill for a guy who helped to be an architect of mass incarceration,” Booker said of Biden.

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He also once again knocked Biden’s proposal, saying “it's an inadequate solution to what is a raging crisis in this country.”

Facing jabs from Booker and other 2020 Democratic nomination rivals over the law, Biden has repeatedly defended many aspects of the measure.

Biden, who remains the front-runner in the Democratic nomination race in part thanks to his strong support from black voters, credited the law’s gun control provisions – including the assault weapons ban – which he said helped him “beat the NRA.”

But on Wednesday he stressed that “every major initiative needs to be reformed.”

“We have now a systemic problem of too many African-Americans in jail, right now. So I think we should shift the whole focus from what we’re doing in terms of incarceration to rehabilitation,” he highlighted. “I don’t think anybody should go to jail because of a drug crime unless they’re a major seller or dealer.”

Biden also called for education programs in prisons.

Later, Biden told reporters that Booker's "police department was stopping and frisking people, mostly African-American men."

He added that during his years as vice president, "the Justice Department took action against them, held the police department accountable. He (Booker) objected to federal interference."

And Biden emphasized he's ready to debate records, but added he'd rather talk about the future.

"If he wants to go back and talk about records, I’m happy to do that. But I’d rather talk about the future," Biden said.

And touting his new criminal justice reform proposal, he said, "I challenge him or anyone else to tell me how he has a better plan that I have for moving from here. It’s about the future."

Two hours later Biden's campaign continued the counter attack.

Biden deputy campaign manager Kate Bedingfield slammed Booker's criticism, saying "the absurdity of this attack is obvious. Almost 90% of all people incarcerated in America are in state and local prisons and jails for violating state laws – laws that Joe Biden, of course, did not write. In addition, the growth of the incarceration rate was slower after the 1994 bill."

And she spotlighted that "at his inauguration as Mayor of Newark in 2006, Booker promised a zero tolerance policy for minor infractions, which is exactly the kind of policy that enmeshed many undeserving people in a criminal justice system that cast a huge shadow over their subsequent lives."

Bedingfield touted that "for decades, Joe Biden has been working on criminal justice reform."

Booker campaign manager Addisu Demissie, picking up on those words, fired back on Twitter, writing "That's the probelm. And that's the tweet."

An error occurred while retrieving the Tweet. It might have been deleted.

The two candidates may tangle again over criminal justice later this week, as both speak in Indianapolis at the National Urban League’s annual conference.

Biden and Booker also will be standing side by side center stage next Wednesday night in Detroit, during the second round of Democratic presidential primary debates.

This isn't the first time the two candidates have thrown verbal punches at each other.

Last month, Booker called on Biden to apologize after controversial comments from the former vice president spotlighting his ability to find common ground in the Senate four decades ago with segregationist senators with whom he vehemently disagreed.

Biden later said Booker owed him an apology.