Setting expectations low and then exceeding them is part of presidential politics -- though often these things are well out of a campaign's control and one doesn't want the bar set too low, for fear of discouraging supporters. In any event, the campaign that has to worry about the bar being set too high for Thursday night is Obama's­ which now probably needs to win or risks heading into New Hampshire with the air seeping out of its balloon.

Part of that is due to last night's Des Moines Register poll that - thanks to its forecast that independents and even Republicans would flood the Democratic caucuses for Obama - gave him a final poll lead no one else has found. But part of it was happening even before this poll. "Obama campaign predicts Iowa win," reads the headline of this morning's Newsday.

"I think Barack Obama needs to win Iowa," said Matthew Dowd earlier on ABC's Good Morning America. Rasmussen has joined the chorus, writing on Monday, "Obama needs to win Iowa if he is to have a shot at the nomination."

The truth is that on paper, Obama doesn't have to win Iowa. (Edwards with far less money probably does.) January is all about momentum; it's in February when the actual delegate selection begins in earnest. Obama could finish second in Iowa, and then certainly go on to win New Hampshire or then South Carolina. Even an Iowa result with the top three tightly bunched wouldn't have hurt him really - at least before the expectation bar got raised.

Now, anything less than an Iowa victory will look like a defeat, unless the story Friday is that Clinton completely crumbled. Maybe Obama's campaign knows something we don't. Or, maybe, getting fired up and ready to go has gotten the better of them.

To read Steven Stark's complete "Presidential Tote Board" blog, go to www.thephoenix.com/toteboard/