(CNN) -- Sen. Hillary Clinton has lost a large amount of support among African-Americans, with a majority of black Democrats now supporting Sen. Barack Obama, according to a new poll out Friday.

Sen. Barack Obama has the support of a majority of black Democrats, a poll found.

In a national survey by CNN/Opinion Research Corp., 59 percent of black Democrats backed Obama, an Illinois Democrat, for their party's presidential nomination, with 31 percent supporting Clinton, the senator from New York.

The 28 point lead for Obama is a major reversal from October, when Clinton held a 24 point lead among black Democrats.

"There's been a huge shift among African-American Democrats from Clinton to Obama. 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 senior political analyst.

"Obama's lead over Clinton among black men is more than 50 points, and among black women, once a Clinton stronghold, Obama has an 11 point advantage," said CNN polling director Keating Holland.

It also appears the recent bickering between Clinton and Obama and their campaigns over race has hurt both candidates. Clinton has the support of 42 percent of all registered Democrats in the new survey, down seven points from last week's CNN/Opinion Research Corp. poll. Obama has the backing of 33 percent of those questioned, down three percentage points in a week.

The beneficiary appears to be former Sen. John Edwards of North Carolina, who jumped 5 points, to 17 percent.

"Why have Clinton and Obama both lost support over the past week? One word: squabbling. If two candidates get into a fight, the third candidate usually gains. Sure enough, John Edwards gained," Schneider said.

Rep. Dennis Kucinich of Ohio is at 3 percent in the new poll, with former Sen. Mike Gravel of Alaska with support of less than 0.5 percent.

In the battle for the Republican presidential nomination, the survey suggests Sen. John McCain remains the front-runner, but his support among registered Republicans has dropped 5 points since last week's survey, which was taken immediately after the senator from Arizona won the New Hampshire primary.

McCain is at 29 percent, with former Arkansas Gov. Mike Huckabee at 20 percent and former Massachusetts Gov. Mitt Romney at 19 percent, up five points from last week. Romney won Tuesday's Michigan primary.

"There was a Michigan bounce," Schneider said. "But McCain still leads. Conservatives, however, are divided between McCain at 26 percent, Huckabee at 24 percent and Romney at 20 percent. Saturday's South Carolina GOP primary should tell us if there's going to be a conservative favorite in this race."

About half the interviews for the new poll were taken before the Michigan primary results were known.

The poll indicates Huckabee may be hurt by perceptions about his leadership abilities.

"Nearly half of registered Republicans say he does not have the leadership skills and vision a president should have. Romney and McCain score much better on this measure," Holland said.

Rudy Giuliani is at 14 percent in the new survey. That's a drop of four points from last week's poll for the former New York mayor.

"Giuliani's support is half of what it was in November, when he last led in the national polls. Giuliani has a problem on issues. Forty-five percent of registered Republicans say they disagree with him on issues that matter to them. McCain ranks highest among registered Republicans on both measures," Holland said.

Former Sen. Fred Thompson of Tennessee has the backing of 9 percent of registered Republicans in the survey, with Rep. Ron Paul of Texas at 6 percent and Rep. Duncan Hunter of California at 1 percent.

Looking ahead to the general election, the GOP has several matters to address. The poll indicates Democrats are much more enthusiastic than Republicans about voting so far this year.

"If that pattern persists, turnout may be a concern for the GOP in November," Holland said.

When all voters nationwide are asked to evaluate the major candidates in both parties, only one Republican candidate, McCain, fares well on issues and personal qualities. Most registered voters say Clinton and Obama -- as well as McCain -- have the necessary leadership skills and vision to be president. But most voters don't feel that way about Romney, Giuliani and Huckabee.

The same is true on issues. A majority of registered voters nationwide say McCain, Obama and Clinton agree with them on issues that matter, but a majority of voters disagree with Romney, Giuliani and Huckabee on important issues.

The economy continues to top the list of the public's biggest concerns, with Iraq, terrorism and health care not far behind. Four in 10 Americans now say the economy is in good shape, down 6 points since December and 14 points since the fall. Nearly six in 10, 59 percent, say the economy is in poor shape.

Regarding Iraq, the number of Americans who say things are going well for the U.S. has jumped 12 points since November, to 46 percent. Support for the war has grown 3 points in the same time.

The poll involved interviews with 1,393 adult Americans, including 448 registered voters who describe themselves as Democrats and 377 registered voters who describe themselves as Republicans. They were interviewed from January 14-17.

The poll's sampling error is plus-or-minus 5 percentage points for the Republican respondents, 4.5 percentage points for the Democratic respondents, and 8 percentage points for the African-American Democrat respondents. E-mail to a friend

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