Your observation is right... but maybe not complete. Is it Congress that has lost the ability to negotiate... or is it American voters who have abandoned negotiation? Isn't it interest that Murray and Ryan are from states where someone of either party can be elected by the voters.
We have a bunch of states where the voters "take no prisoners" as the old cliche goes. I refer you to the current news story of Eric Cantor. If you have a bunch of voters back home with the "lynch mob mentality"... why would you on the best day of your life think you could compromise in Congress.... and (politically) live to tell about it.
It it real easy for all of us to sit home and yell "Throw the bums out!" about our Congressmen. But are we willing to put a little yard-sign up for a congressman or senator of the minority party in our own yard. I guess this is the year I get to face that question in my own neighborhood.
If I am too chicken to put an unpopular campaign sign in my yard, why would I have any dreams that my congressman would actually sit down and negotiate in Washington?
Something is lost on THE POPULACE today.