Donald Trump made a sustained pitch Friday to African American voters, who have overwhelmingly flocked to his Democratic rival Hillary Clinton, telling them: "what do you have to lose?"

The Republican presidential nominee, who languishes in the polls both nationwide and in virtually every battleground state, faces an uphill battle to broaden his support base if he is to avoid a Democratic landslide in November.

"No group in America has been more harmed by Hillary Clinton's policies than African Americans," Trump told a rally in Dimondale, Michigan.

"If Hillary Clinton's goal was to inflict pain on the African American community, she could not have done a better job. It's a disgrace," he added.

He told the crowd that he was asking for the vote of "every single African American citizen in this country who wants to see a better future."

"Look how much African American communities have suffered under Democratic control. To those I say the following: what do you have to lose by trying something new like Trump?" he said.

The New York billionaire, whose controversial run for the presidency has attracted white supremacists, alienated immigrants and done little to win over minorities, said blacks were living in poverty facing disproportionately high unemployment rates and without good schools.

"Your schools are no good, you're living in poverty... What the hell do you have to lose?" Trump repeated.

African Americans voted overwhelmingly in favor of outgoing Democratic President Barack Obama and Clinton's husband, former president Bill Clinton.

In 2012, Republican nominee Mitt Romney won only six percent of the black vote.