The messages were quickly removed after being flagged by users and have been seen by only a small number of people on the site, Schnitt said. "Facebook is not a very effective way to do this," Schnitt said, adding that the company plans to refer the messages to law enforcement.

Youth voting group says voters in Florida, Arizona, Colorado, Utah and Pennsylvania have received on their mobile phones, reading: "Due to long lines tomorrow, all obama voters are asked to vote wednesday. thank you."

E-mail hacking has come into play, too.

About 35,000 students at George Mason University were sent a fake e-mail early Tuesday, also telling them to vote on Wednesday. The message appeared to be from the school's provost, Peter Stearns. According to the , a hacker managed to route this message to the university via servers at wiredforchange.com, a Democratic fundraising company based in Washington, D.C.

"To the Mason Community," the fake e-mail reads. "Please note that election day has been moved to November 5th. We apologize for any inconvenience this may cause you."