Former President Bill Clinton faced down protesters angry at the impact his crime reforms of 20 years ago have had on black Americans and defended the record of Hillary Clinton, his wife, who is relying on the support of black voters in her quest for the presidency.

The former president spent more than 10 minutes confronting the protesters at a campaign rally in Philadelphia for his wife on Thursday over criticisms that a 1994 crime bill he approved while president led to a surge in the imprisonment of black people.

The Democratic race for the Nov. 8 election has become increasingly heated as Hillary Clinton, stung by a string of losses in state contests, has traded barbs with her rival for the party's nomination, U.S. Sen. Bernie Sanders, over who is better prepared for the White House.