Former President Bill Clinton said Friday that he regretted drowning out the chants of black protesters at a rally in Philadelphia the day before, when he issued an aggressive defense of his administration’s impact on black families. His reaction thrust a debate about the 1990s into the center of his wife’s presidential campaign, one that has focused heavily on issues of race and criminal justice.

“I know those young people yesterday were just trying to get good television,” Mr. Clinton said Friday of the Black Lives Matter protesters who had accused him and Hillary Clinton of supporting policies that devastated black communities. “But that doesn’t mean that I was most effective in answering it.”

His statement did not quiet a raging storm of criticism. Still, it was a remarkable reversal for Mr. Clinton, who occupies a singular role in his wife’s campaign as a spouse and a popular former president who can sometimes make himself into a lightning rod. He has had to campaign for his wife in an era when signature policies of his administration have been repudiated both by Mrs. Clinton and her opponent, Senator Bernie Sanders of Vermont.

None of those issues has been more central to the 2016 campaign than the 1994 crime bill, which created tougher penalties for nonviolent drug offenders, erected dozens of new prisons, banned certain types of assault weapons and sent 100,000 more police officers to American cities.