Will The Conservatives Out Perform The Polls?
Nate Silver sketches out various scenarios:
My intuition is that most of the risks are still to the downside on Labour's vote, given the history of overestimating their vote in the past and that some pollsters are distributing undecideds based on how people claimed to have voted in the last election -- something which tends to help Labour because their voters seem the most indifferent about this election. On the other hand, our model is more aggressive than most others in taking away seats from Labour for a given vote share.
As of this writing, betting markets now give Conservatives about a 38 percent chance of claiming a majority. I don't know that there's much arbitrage either way there, but I'd be slightly inclined to take the Tories on those odds.
Ruffini, booster of conservative chances, predicts that the "Tories wind up with 328 seats and the chance to form a Government outright."