When the sitting vice president guns down the former treasury secretary on a beach in New Jersey, politics might be broken. (Then again, let's also concede that dueling is, in general, more honorable than relying on 527s to do your dirty work.) But if Democrats, only a year after hosannas rained down on their man, aren't getting their way, it is no reflection on the system.
In fact, at the same time partisanship is unseemly, it is generally constructive. It is also the normal state of being. The two-party system, with all its obvious faults, allows most of you to vote for some generally acceptable envoy to advocate for whatever ideological belief system you've decided on that election cycle.
In this system, two powerful parties of consensus try to destroy each other and, at the same time, keep an eye on polls. And if polls are any indication, it seems as if the process is working quite well these days.
So relax; the republic will survive -- with partisanship and without Evan Bayh.