WASHINGTON -- This year's flood of newly registered voters heavily favor Sen. Barack Obama in the presidential contest, but they won't necessarily show up to support him on Election Day, a new survey indicates.

A nationwide poll of Americans who are eligible to vote for the first time, or who skipped the previous election but are registered now, found that they back Sen. Obama over Sen. John McCain by a margin of 61% to 30%. (See full poll findings.)

The survey, conducted by the Wall Street Journal, NBC News and the MySpace networking Web site, also found these voters have distinctly more positive impressions of Sen. Obama than any of the other three candidates atop the Democratic and Republican tickets.

But that hardly means the Obama campaign can count on them. When asked to rank their interest in the Nov. 4 election, just 49% said they were "very interested." By comparison, 70% of voters of all age groups said they were "very interested," according to a separate Journal/NBC News national poll taken a week ago.

Moreover, 54% of the new voters said they would definitely vote Nov. 4.