(and before the Secret Service shows up, let me be clear: i mean the kamikaze primary challenge)

Ezra Klein, quoting Steve Benen:

[I]magine there's a big meeting with every member of the Democratic caucus in both chambers. You stand at the front of the room and make a presentation: "If health care reform falls apart after having come this far, tens of millions of Americans will suffer; costs will continue to soar; the public will perceive Democrats as too weak and incompetent to act on their own agenda; the party will lose a lot of seats in the midterms and possibly forfeit its majority; and President Obama will have suffered a devastating defeat that will severely limit his presidency going forward. No one will even try to fix the dysfunctional system again for decades, and the existing problems will only get worse."

For progressive Democrats, the response would be, "That's an unacceptable outcome, which we have to avoid."

For conservative Democrats, the response would be, "We can live with failure."

This necessarily affects negotiations. One contingent wants to avoid failure; the other contingent considers failure a satisfactory outcome. Both sides know what the other side is thinking.

That's Steve Benen, describing the dynamic in the Senate. As I've said before, I think a lot of folks imagine this as a negotiation, in which both sides want to get to yes, and so everyone is involved in a complex game to signal their comfort with failure in order to strengthen their ultimate bargaining position. But that's not an accurate depiction of the process.

If this is comparable to any form of negotiation, it's a hostage negotiation. The hostage-takers might not prefer to kill the kid, but there's definitely some upside to killing the kid, as it strengthens them in future negotiations. Conversely, the people on the other side of the phone don't want the kid to die, but also don't want a situation in which hostage-taking is encouraged. Generally, you try and resolve that by killing or capturing the hostage-takers, but that's not really an option here, with the closest analogue being a kamikaze primary challenge against Blanche Lincoln, which would come too late to affect health-care reform anyway.