WASHINGTON (AP) — Joe Biden acknowledged Wednesday that questions raised about his support for the 1994 crime bill are "legitimate." But the presumptive Democratic presidential nominee insisted that people should judge him based on his current actions, not his past.

Speaking during a virtual NAACP forum, Biden responded to questions that the moderator said were from young voters concerned about his role in writing the bill when he was a senator from Delaware. Critics say the tough-on-crime bill contributed to the mass incarceration of racial minorities in recent decades.

Biden, growing testy, acknowledged that "it's a legitimate concern, they should be skeptical." But he also said that while he's been "told all along" that young people oppose his past stances on criminal justice issues, "there is no polling evidence to sustain that. Nor is there voting evidence thus far to sustain that."

"Watch what I do. Judge me based on what I do, what I say and to whom I say it," he said.

Black voters remain key to Democrats' chances for victory this fall, and Biden has engaged in a concerted outreach effort to the black community, releasing a plan focused on black economic mobility and racial disparities in health care and education systems earlier this year. He has also issued a criminal justice plan that reverses a number of key provisions of the crime bill and has apologized for supporting some policies in the 1990s that he now says were harmful.

But some black voters are still angered by his past stances on criminal justice issues and have questioned whether his proposed reforms go far enough.

While there's little chance black voters will support President Donald Trump in significant numbers — 6% of black voters supported Trump in 2016, according to a Pew Research Center analysis of people who participated in its polls and were confirmed to have voted — there are concerns they may stay home, which could make the difference in a number of states key to Democrats' White House hopes.

Still, Biden predicted Wednesday night that Democrats may be poised to take back control of the Senate this fall, if the current political climate continues.

"Based on the polling data now — it's really early — there is a real prospect that we'll pick up up to six seats in the United States to win back the Senate," he said.

As the police killing of George Floyd in Minneapolis sparked nationwide protests and a renewed push for criminal justice and policing reform, Biden has spoken out more forcefully for the need to address systemic racism, and he reiterated his call for a number of police reforms first outlined in his criminal justice plan last summer.

But on Wednesday night, he still avoided a major flashpoint in the conversation around such reforms — whether he'd support reparations for black Americans. Pressed multiple times on his stance, Biden said only that a study should be done and that his support for cash reparations "would depend on what it was and if it will include Native Americans as well."