MILWAUKEE: Democrats Hillary Clinton and Bernie Sanders were reaching out to the key black and Latino vote on Friday after a debate that marked a campaign shift toward states with more minority voters. Most candidates from both parties were focusing on South Carolina, whose primaries later this month begin the critical race for southern voters.

The Democratic rivals spent much of Thursday's debate in a respectful discussion of their marginal differences on issues like immigration and criminal justice reform. Both were animated on a fundamental question facing Democrats: has President Barack Obama gone far enough in his policies?

Clinton, who has cast herself as the rightful heir to Obama's legacy, accused Sanders of diminishing the president's record. Sanders has suggested Obama hadn't succeeded in closing the gap between Congress and the American people — something Obama has acknowledged.

"The kind of criticism I hear from Senator Sanders, I expect from Republicans. I do not expect it from someone seeking the Democratic nomination," Clinton said.

Sanders responded by noting that Clinton ran against Obama in the 2008 presidential race.

Long viewed as the overwhelming front-runner in the Democratic race, Clinton has been caught off-guard by Sanders' connection with Americans frustrated by the current political and economic systems. The former secretary of state's connections to Wall Street have given Sanders an easy way to link her to his call for a "revolution."

Clinton's campaign has argued that the Vermont senator's appeal is mostly limited to the white, liberal voters who gave Sanders a win in New Hampshire and a close second-place finish in Iowa.

The race turns now to Nevada, South Carolina and other more diverse states including Alabama, Georgia, Tennessee, Arkansas and Texas.

Seeking to boost his support with minorities, Sanders called for reforms to a "broken criminal justice system" that incarcerates a disproportionate number of minorities.

Clinton concurred on a need to address a criminal justice system, but she cast her proposals for fighting racial inequality as broader than his.

"We're going to emphasise education, jobs and housing," said Clinton, who was endorsed earlier in the day by the political action committee of the Congressional Black Caucus.

The candidates both vowed to pursue comprehensive immigration reform, using the emotional issue to draw a contrast with Republicans who oppose allowing many of the millions of people in the United States illegally to stay.

Both disagreed with a new series of raids authorized by Obama to arrest and deport some people from Central America who recently came to the country illegally.

"We should be deporting criminals, not hardworking immigrant families who do the very best they can," Clinton said.

Clinton is hoping to offset Sanders' backing from young Americans who like his call for free tuition at public colleges and universities and a plan for a government-run, single-payer health care system. Clinton said those proposals come with unrealistic price tags.

Sanders didn't shy away from the notion that he wants to expand the size of government.

"In my view, the government of a democratic society has a moral responsibility to play a vital role in making sure all our people have a decent standard of living," Sanders said.

While Clinton is trying to become America's first female president, it was Sanders — a democratic socialist who would be the first Jewish president — who tried to drape his candidacy in a bit of history, saying: "I think a Sanders victory would be of some historical accomplishment as well."