WASHINGTON — Sen. Cory Booker, D-N.J., questioned Sunday whether former Vice President Joe Biden could be a uniter on race if he wins the Democratic presidential nomination, accusing Biden of having an “inability to talk candidly about the mistakes he made.”

Booker, who has been one of Biden's most outspoken critics in the Democratic field in recent days, pointed to a handful of examples — Biden's opposition to federally-mandated busing as a tool of desegregation in the 1970s, recent comments about his working relationship with senators who supported segregation, and his defense of the 1994 crime bill — to argue that the former vice president "is not doing a good job of bringing folks together."

“Whoever our nominee is going to be, whoever our next president is going to be, really needs to be someone who can talk openly and honestly about race," Booker said during an appearance on "Meet the Press."

"I’m not sure if Joe Biden is up to that task given the way the last three weeks have played out.”

Booker's comments came in the wake of the high-profile clash on the debate stage last week between Biden and Sen. Kamala Harris, D-Calif., over the issue of busing.

Harris said it was "hurtful" for Biden to recently evoke his relationships with former Sens. James Eastland, D-Miss., and Herman Talmadge, D-Ga., both of whom were strident segregationists.

Noting that she was a part of an early wave of busing minority children to other schools, Harris took issue with Biden's efforts to block federally-mandated busing.

Biden responded by saying that Harris' comments were a "mischaracterization of my position across the board," arguing that he has a long record of fighting for civil rights and that he saw busing as a local issue, not one to be decided at the federal level.

During his interview Sunday, Booker also brought up Biden's work on the 1994 crime bill, a tough-on-crime approach from which many Democrats have walked away.

Booker said the issue is less about Biden's role in passing legislation and more about how he still defends it.

"A lot of Democrats who were involved with the 1994 came bill have spoken very openly and with vulnerability, talking about their mistakes," Booker said.

"That doesn’t disqualify you. But what we’ve seen from the vice president over the past month is an inability to talk candidly about the mistakes he made, about things he could have done better."

Biden defended his civil rights record during a Friday event with Rev. Jesse Jackson Sr.'s Rainbow PUSH coalition.

"I want to be absolutely clear about my record and position on racial justice, including busing. I never, never, ever opposed voluntary busing," he said, drawing the same distinction that he did during the debate about the difference between opposing a federal mandate to bus and arguing the decision should be made at the local level.

"I did support federal action to address root causes of segregation in our schools and communities, including taking on the banks, and redlining and trying to change the way in which neighborhoods were segregated," he added.

"I've always been in favor of using federal authority over common, state-initiated segregation."