"If you care about politics and spend a fair amount of time online," says Mark Blumenthal at The Huffington Post, "odds are good that sometime between 5 pm and 7:30 pm Eastern time on Tuesday, you will encounter someone sharing leaked 'exit poll' numbers that purport to tell you who will win various battleground states." You should resist temptation and "try to ignore them, at least until the polls close. And even then, take the underlying vote estimates with big grains of salt." 

This is actually a rare point of agreement between the campaigns of President Obama and Mitt Romney. On Monday, Obama spokeswoman Stephanie Cutter urged the president's supporters to "keep calm and tweet on... no matter what you hear tomorrow about turnout in Republican counties or exit polls, particularly early in the day." 

Hmmm, that's an awful lot of cold water from "such an ostensibly confident, feelin'-good campaign," says Erika Johnsen at Hot Air. If Team Obama were so sure of victory, it wouldn't worry about "any potential late-in-the-day Democratic voters [being] dissuaded from getting to their polling stations by poor news or spreading pessimism."

It's Republicans who should worry about "someone in the press, perhaps even at one of the big networks," leaking exit polls showing Obama winning the election, says Tom Blumer at NewsBusters. In a woefully under-reported bit of news, the networks and news organizations (which traditionally conducted exit polls in 50 states) are discontinuing exit polling in 19 states this year — including 15 safely Republican states. So of course the exit polls "will clearly show Obama leading Romney (if they don't, we're looking at a Romney landslide of epic proportions)," and that could easily "create accidental or deliberate Election Night confusion which favors the incumbent."

Exit polls have never been good at "predicting what will happen in the various states," and that's not their purpose, says Jonathan Bernstein at A Plain Blog About Politics. Exit polls can be useful, after the fact, in analyzing exactly what happened. Before that, however, they're nothing more than rough estimates:

Even worse, the initial exit polls you'll hear about are still partial, with additional waves coming at the end of the day. Not to mention that I've seen false "leaked" exit polls more than once; of course, that's not the fault of the polls themselves, but it is yet another reason to be cautious of numbers that are in no way official. You'll know soon enough. The extra two or three hours of having an additional, very dubious, hint, just isn't worth anything.