The poll shows 45 percent of Democrats and Democratic- leaning voters said they would most like to see Obama nominated for the presidency, compared with 44 percent who favored Clinton. The difference is well within the 5 percentage-point margin of error for Democrats in the survey.

Obama, an Illinois Senator, previously had a commanding lead in most national surveys after 11 consecutive victories in February's primaries and caucuses. Clinton, a New York Senator, revived her campaign by winning in Texas and Ohio on March 4.

Senator John McCain of Arizona, who won the Republican nomination this week, appears to be benefiting from the battle being waged between the Democratic candidates. Twenty-five percent of Clinton supporters and 20 percent of Obama supporters told Newsweek that they would vote for McCain in the general election if their candidate wasn't on the ballot.

The poll suggests that Clinton and Obama may fare best in November on a combined ticket regardless of who runs at the top, a prospect supported by 69 percent of Democrats surveyed, Newsweek said.

Almost half of Democrats surveyed said the most important issue in the election is the economy and jobs, while one-fourth cited health care and 16 percent said the war in Iraq. More Democrats said they trusted Clinton to handle the situation in Iraq and reduce health-care costs. The candidates were tied on the issue of improving the economy.

The poll of 1,215 registered voters was conducted by telephone March 5-6. It has an overall margin of error of plus or minus 3.5 percentage points, and plus or minus 5 percentage points for the 573 Democrats surveyed.

By Catherine Larkin, Bloomberg, March 8, 2008