US Democratic White House hopeful Barack Obama on Monday urged blacks to take more responsibility for improving their own lives, standing firm on a tough message that has been criticized by some African Americans.

Obama, who would be the first black US president if elected, was accused by civil rights leader Jesse Jackson last week of "talking down to blacks".

"Now, I know there's some who've been saying I've been too tough, talking about responsibility," Obama told the NAACP, the nation's oldest civil rights organization. "I'm here to report, I'm not going to stop talking about it."