When President Obama and campaign aides finally hit the sack early Tuesday in Chicago, they were supremely confident. But if they were to be beset by one nightmare, said two confidantes, it was an unforeseen, large turnout of white voters for Mitt Romney.

Air Force One was scheduled to arrive shortly after midnight at O’Hare International Airport, ending a frenetic, exhausting and nostalgia-ridden final election journey for Obama and many who have traveled with him since he announced his underdog candidacy in the cold of Springfield, Illinois. in 2007.

Campaigns can often be breeding grounds for confidence bordering on self-delusion. And so it was not a great surprise Monday to talk to insiders in both camps and hear an optimism that can’t be reconciled.

Even with their public spin and private declarations in sync, their analyses of what will happen on Election Day suggested they inhabit alternate universes.

Ohio? Members of both camps claimed they are convinced they will win. Virginia? Ditto.

The specifics of their predictions included a county here, a county there, how it went in 2008 and how things would be different this time or, perhaps, the same. Confidence in their respective statistical models of turnout were no less compatible than the two candidates’ takes on immigration reform.

But the president’s team was not worry-free. One campaign official and one adviser to the inner Obama circle had similar responses when asked what their single greatest anxiety was, if there was one. In each case, it involved the decline in white support for Obama since his victory over Sen. John McCain four years earlier, especially among men.

Obama and McCain were roughly even among whites going into the election. Romney now has a substantial lead—in the vicinity of 14 or so points.

What do you most fear, I asked. Said one: “A huge white turnout. Kind of like what Bush hit us (John Kerry) with in ’04.”

The Obama constituency is primary black, Hispanic, single females and well-educated urban whites. Polling suggests black and Hispanic are overwhelmingly Democratic in the same percentages as four years ago; roughly 90 percent for blacks and more than 70 percent for Hispanics.

But if even his overwhelmingly pro-Obama hometown is an indicator, turnout among those groups won’t be quite the same as four years earlier. Local election officials said Monday that turnout will simply not be as heavy as 2008 when some 74 percent of registered voters showed up at the polls.

That reality, combined with at least the possibility of a white-dominated, pro-Romney surge, was the cause of stress for Obama’s re-election strategists. Still, those worries did not overwhelm their conviction that the president has a virtual lock on the Electoral College vote—and that Romney faces a complex uphill path to victory.