I agree with the game-theoretic principle here, which I assume is the part of relevance to LessWrong, but in the interest of mandatory token disagreement: the stated expectations of voters are probably an extremely bad guide to the actual expectations of policymakers, and when either party does achieve a trifecta they very swiftly moderate what has been portrayed as their "full agenda." Barring extreme external events Ryan-style budget cuts aren't going to happen.
when either party does achieve a trifecta they very swiftly moderate what has been portrayed as their "full agenda."
In US national politics, I suspect that the least secure incumbents in Congress are also those that are closest to the "center" between the two parties, and that when they're replaced, they're often replaced by similar "centrists", so the median ideological position of the parties doesn't change much.
I also imagine that under parliamentary systems in which people vote for parties rather than individuals, this isn't the case.
Related to: Politics is the Mind-Killer
Both sides seem to have a stake in the current budget supercommittee failing. Why?
The NYTimes reports:
In other words, the Republicans believe they can achieve complete victory so that they can enact their whole agenda, while Democrats believe they can block this victory.
On a key component — Obama's re-election — Republicans believe they will defeat Obama with 1:6 odds, while Democrats believe this event has only 3:2 odds.**
With a 9-fold difference in this key perception, it seems highly unlikely the two will reach a compromise.
* Not necessarily true — you can't just multiply 74%*72%*83% as these events have high positive correlations.
** Yes, perhaps the people in power have different perceptions than the rank-and-file electorate — but they still must win their base's support to gain re-election.