Obama, coming off 11 straight primary and caucus victories, had the support of 54 percent of Democratic primary voters nationally. Clinton had 38 percent support.
In a CBS News poll taken three weeks ago, shortly before Super Tuesday, Obama and Clinton were tied at 41 percent. Clinton led by 15 points nationally in January.
The former first lady has lost her advantage among women, according to the poll: The two leading Democrats now have even levels of support among female primary voters.
Men, meanwhile, disproportionately favor Obama. He leads Clinton among male Democratic primary voters 67 percent to 28 percent, and leads among white men 61 percent to 33 percent.
Fifty-nine percent of Democratic primary voters said Obama has the best chance of beating likely Republican nomineein the general election. Twenty-eight percent said Clinton is most likely to win in November.
Obama is now seen as the likely Democratic nominee: More than two-thirds of Democratic primary voters said they expect the Illinois senator to win the nomination.
When all registered voters were asked who they favored in a head-to-head general election match up between Obama and McCain, Obama led by 12 percentage points, 50 to 38 percent.
In a Clinton-McCain match up, registered voters were evenly split, with 46 percent backing each candidate.
Obama beats McCain by 10 points among independents, while McCain beats Clinton by 17 points among that group.
Democrats Say Differences Between Obama, Clinton Aren't On The Issues:
Democratic primary voters do not see significant differences among Clinton and Obama on two of the issues most important to them: Majorities of those polled see only "minor" differences between the two on the war in Iraq and health care.
But Democratic primary voters were more likely to identify Obama as someone who cares about them "a lot" (63 percent for Obama vs. 46 percent for Clinton), someone who makes them feel inspired about the future (69 percent for Obama vs. 54 percent for Clinton), someone who would compromise the right amount with Republicans to get things done (67 percent for Obama vs. 55 percent for Clinton), and someone who could bring change to Washington (70 percent for Obama vs. 60 percent for Clinton).
Bill Clinton's involvement in the race has split Democrats. The percentage of primary voters who said the former president's involvement has made them more likely to support Hillary Clinton - 22 percent - was equal to the percentage who said it made them less likely to support the former first lady. 55 percent said it made no difference.
Read The Complete CBS News Poll On The Democratic Race
The General Election
The Economy And War In Iraq
A majority of Democratic primary voters said that the superdelegates - the party insiders who could decide the nomination if the race remains tight - should back whichever candidate gets the most overall elected delegates. A quarter said they should back whomever they want, while 20 percent said they should back the candidate with the best chance to win in a general election.
Republicans Accept McCain, But Enthusiasm Lacking:
On the Republican side, more than 80 percent of primary voters said they would be satisfied with McCain as their nominee - but less than 30 percent would be "very satisfied." The findings suggest a far lower level of enthusiasm than exists among Democratic primary voters, roughly four in 10 of whom would be very satisfied with Clinton or Obama as their nominee.
A majority of Republican primary voters said McCain generally has the right positions on the issues, though self-described conservatives were less enthusiastic: 52 percent said the Arizona senator is not conservative enough.
Almost three-quarters of Republican primary voters - including 60 percent of conservatives - want a candidate who would compromise with Democrats in order to get things done. Only 14 percent said they want a Republican president who will stick to Republican positions even if it means getting less accomplished. A majority said they believe McCain would compromise the right amount as president.
McCain Seen As Prepared, But Obama Viewed As Uniter:
Voters said the best age for a president of the United States is in their 50s. Obama, at 46 years old, is the youngest candidate in the presidential race; McCain, at 71, is the oldest. Hillary Clinton is 60 years old.
Of the three, McCain is seen as most prepared to be president: 73 percent of registered voters said he was prepared for the job. Clinton was seen as prepared by 57 percent of registered voters, and Obama was described as such by only 39 percent. More than half said Obama needs more time.
Roughly two-thirds of registered voters said Obama would unify the country, however. About half of registered voters said McCain would do so and about one-third said the same of Clinton. More than half of registered voters said Clinton would not do so.
McCain is seen as the strongest commander in chief: Nearly half of registered voters said it was "very likely" that he would be an effective commander in chief. Less than one-quarter said the same of Obama and Clinton. Fifty-six percent said they were confident in McCain's ability to handle an international crisis, while less than half said the same of Obama and Clinton.
Obama is seen as most likely to improve foreign relations, however. Nearly a third of registered voters said he was very likely to do so. Twenty three percent said Clinton was very likely to improve foreign relations, while just 16 percent said it was very likely McCain would do so.
Clinton is the only candidate of the three to have a higher unfavorable rating than favorable rating among registered voters. Thirty-five percent view the former first lady favorably, while 43 percent view her unfavorably. Obama is viewed favorably by 45 percent and unfavorably by 23 percent. McCain is viewed favorably by 36 percent and unfavorably by 32 percent.
Pessimism Over Economy, But Growing Optimism Over Iraq:
The economy was cited by 33 percent of Americans as the most important problem facing the country, more than any other issue. The Iraq war was cited by 20 percent. On Iraq, voters give McCain a slight edge over Obama on the ability to make the right decisions. Voters who think U.S. action in Iraq was the right thing are more likely to express confidence in McCain, while those who think we should have stayed out are more apt to express confidence in Clinton and Obama.
Seven in 10 Americans believe the economy is in bad shape. Sixty-three percent believe it is getting worse, and one in four said it is presently in very bad shape. A year ago, only 35 percent said the economy was in bad shape. More than three-quarters of Americans say their household is faring well financially, however.
A majority of voters said they were at least somewhat confident in all three candidates to make the right decisions on the economy. Those who think the economy is in good shape express more confidence in McCain to handle the issue, while those who think the economy is in bad shape give higher marks to Obama and Clinton.
There is growing optimism about the situation in Iraq, with 43 percent of Americans saying things are going at least somewhat well for the United States there. That represents a five point increase since the beginning of the month and the highest rating since the summer of 2006. But nearly six in 10 Americans said the United States should never have gotten involved in Iraq in the first place.
President George W. Bush's job approval rating is now 30 percent, up three-points from his all-time low of 27 percent, first reached last summer. His approval rating when it comes to handling the economy remains below 30 percent, despite an economic stimulus package that will include rebates for many Americans. Thirty-one percent of Americans now approve of how the president is handling the war in Iraq, up five points from December.
This poll was conducted among a random sample of 1,266 adults nationwide, including 1,115 registered voters, interviewed by telephone February 20-24, 2008. The error due to sampling for results based on the entire sample, and the sample of registered voters, could be plus or minus three percentage points. The error for subgroups is higher.