Charlie Cook has a nice piece up at National Journal noting that congressional leadership is working to avoid forcing their members to take "politically costly votes."
This is an oft-overlooked fact. I think the only flaw in Cook's piece is the suggestion that this is something new. It may not have been as easy for leaders to protect their flock when the parties were less ideologically homogenous, but this is a natural feature of, well, democracy.
We elect people to office. They want to get re-elected. The threat of not getting re-elected is the key element of democratic accountability. But some votes will make it hard for politicians to get re-elected. Those votes are called "politically costly," and parties avoid them. The Democratic Party avoided civil rights for a generation because it was politically costly. Slavery was held off the agenda because it was politically costly.
So it's disappointing to call politicians "wimps" for paying attention to the incentives that democracy provides. And it's just inaccurate to say that if they were "bold" or "dynamic," it would be "refreshing" and we would reward them. No, we (collectively speaking) would not. They'd lose their seats. That's what it means for a vote to be "politically costly."