Jim Messina, President Obama's campaign manager, spoke by conference call to more than 100 members of his Virginia staff last Sunday night to ask whether they're meeting their door-knocking, phone-calling and voter-registering goals -- and to urge them: "Now is the time to push even harder."

The next night, the call was to Colorado. On Wednesday, he met with Senate Democrats to deliver a similar message. And on Saturday, he traveled to Wisconsin to meet with field organizers, neighborhood team leaders and other volunteers there.

"Ignore the polls," Messina said on the call to Virginia, he recalled. "There are always going to be polls showing us up. There are always going to be polls showing us down. None of that matters. What matters is your voter contacts in your state."

Recent polls may show Republican Mitt Romney trailing Obama in pivotal states, including Ohio and Virginia, but his campaign said there is an ongoing danger for the president: That his supporters will take his apparent advantages for granted and fail to show up on Election Day.

They say they have been aided by Democrats' deep concern over Romney's policies, lack of details and choice of running mate in Rep. Paul Ryan. All of it has inspired Obama backers to redouble their efforts to stay engaged.

"I'm very scared about this election," said Ann Fremgen, 59, a retired teacher from Golden, Colo. "I would be devastated if Romney were elected. ... I am talking to people. I am here today. I have not volunteered yet, but I am going to."

Obama's advisers view complacency as a special threat because they have built so much of their strategy around a vast field operation to register new voters, urge them to the polls or persuade that tiny band of undecided Americans to choose Obama. The effort is entering crunch time now, with registration deadlines looming and early voting already underway in a few states. But it is an effort that depends heavily on the energy and enthusiasm of thousands of field workers and volunteers. Anything that could suppress that enthusiasm -- like the idea that Romney is sunk -- makes nerves jangle in Obama's Chicago headquarters.

And they are facing a torrent of media coverage -- and comedy routines -- reinforcing the narrative that momentum favors Obama. "The Daily Show's" Jon Stewart won't stop talking about Clint Eastwood's now-infamous monologue with a chair.

Worse for Obama, the political activists who make up his field operation pay more attention to this stuff than the electorate overall. "Overconfidence is dangerous," Bill Burton, who leads an independent super PAC supporting Obama, said in a tweet this week. "If you just think of the things that happened in the last 10 days or so, there's a lot more time for a lot more developments. ... Everything can change in a second in this race."