1/ Hopefully partisan politics. That's kinda why they were elected. "Bipartisanship" is just another name for "collusion". Colluding usually means getting part of the blame, so that the next election cycle voters choose "outsiders" rather than the compromising "centrists".
2/ I mention this because there are areas of compromise. If what you care about is "climate change", then Republicans will compromise on a "revenue neutral carbon tax" (where additional revenue offset by tax cuts elsewhere).
3/ On the other hand, there is no way to compromise on things like "gay marriage", or only partial prejudice against gays.
4/ Bipartisanship and compromise aren't real principles that you can abstractly measure. They are instead childish complaints leveled at the other side. Republicans will use them to complain why Democrats won't agree to Republican bills.
