In a conference call this afternoon, President Barack Obama’s re-election campaign had one central message for their supporters when Election Day arrives tomorrow: They should “keep calm,” even if they hear snippets of information favoring Republican Mitt Romney.

“My warning, we need to stay calm for much of the day,” Stephanie Cutter, Mr. Obama’s deputy campaign manager, said, touting thousands of early ballots already submitted by voters. “We’ve already banked a pretty big portion of our vote.”

The fear, she explained, was early numbers leaking before voters have finished going to the polls, creating unnecessary panic and pessimism among Democrats.

“Keep calm and tweet on,” Ms. Cutter said. “So, no matter what you hear tomorrow about turnout in Republican counties or exit polls, particularly early in the day, please remember and remind your readers that, because of early votes, we’re where we need to be to win … I don’t think there’s going to be official exits until the end of the day, but if things leak out that aren’t validated or weighted, please stay calm.”