Fifty-nine percent of those interviewed for the CNN/Opinion Research Corp. poll said they supported Obama, a Democratic senator from Illinois, while 31 percent supported Clinton, D-N.Y., CNN reported Saturday.
That is a major reversal from October, when Clinton held a 24-point lead among black Democrats interviewed for the poll.
"African-American Democrats used to be reluctant to support Obama because they didn't think a black man could be elected. Then Obama won Iowa and nearly won New Hampshire. Now they believe," said Bill Schneider, CNN's senior political analyst.
On the Republican side, the poll suggests Sen. John McCain of Arizona remained the front-runner among all registered GOP voters interviewed for the survey. McCain garnered 29 percent, with former Arkansas Gov. Mike Huckabee at 20 percent, former Massachusetts Gov. Mitt Romney at 19 percent, former New York Mayor Rudy Giuliani at 14 percent and former Sen. Fred Thompson of Tennessee at 9 percent.
In all, 1,393 adult Americans were interviewed from January 14-17. The poll had a margin of error of 5 percentage points for the Republican respondents, 4.5 points for the Democratic respondents, and 8 points for the black Democrat respondents.