There is no Fiscal Cliff deal yet, because there's too much time until the countdown.
Unlike with the debt ceiling, where it really did look like there was an intractable disagreement between the two sides, in this case, the endgame for both is fairly easy to imagine. Taxes stay low for most people. Some spending cuts are made now, and others are made in the form of entitlement tweaks that kick in way down the line.
But there's a lot of politicking to do in the meantime, and there's no reason to let a deal get in the way of scoring points.