CHARLOTTE, N.C. - As buoyant Democratic delegates head home from their three-day convention here to nominate President Obama for a second term, party officials and advisors are sweating the reality that the 2008 hope and change thrill is gone--and so might be Obama's voting majority.

While Obama and Mitt Romney remain locked in public polls, several Democratic officials are worried that three groups that pushed Obama over the finish line in 2008--younger voters, seniors and "Walmart" white women--are as frustrated as other groups about the economy and Obama's failure to change Washington and might stay home.

In other words, they say, the polls lie. Yes, when called by pollsters, the nation is split, but the GOP appears more eager and willing to follow through and vote than the Democrats.

During an event hosted by National Journal/Atlantic her this week, Democratic pollster Celinda Lake cited an "enthusiasm gap" with younger voters and unmarried women and seniors. Former Clinton aide Maria Echaveste said that "too many [Obama supporters] are not engaged." And micro-targeting expert Laura Quinn said younger voters especially are "not motivated as they need be."

As a result, Team Obama has stepped up their get out the vote and registration efforts, but worry that another downturn in the economy could stall that effort.

And some think it could get worse. Highly-respected Democratic Pollster Stan Greenberg said that his data indicates that the "nagging economy" is "still weakening," and that might push any of Obama's must-have groups out of reach, maybe over to Romney. "There's some probability, in fact one-third, that some group could just go and say 'Enough,'" he said.

Naturally, all of that is music to the ears of the Romney campaign, which is clinging to similar data in polls that show Obama's magic has gone. They cite an August Washington Post/ABC News poll that only 78 percent of the president's 2008 supporters back him now. By comparison, 91 percent of Sen. John McCain's backers support Romney.