There are always histrionics, posturing, game-playing and brinksmanship in end-game negotiations. That is probably why financial markets were so serene for months as the debt limit fandango unfolded; it was, or appeared to be, business as usual.

To many of us who have been around Congress for several decades, though, this was not business as usual. In other debt limit dynamics we had blatant posturing and outrageous hypocrisy: politicians' statements of disgust with fiscal profligacy, along with those saying we had to suck it up and be responsible to preserve the U.S.'s credibility and integrity, could be flip-flopped or interchanged across party lines, depending on which party held the presidency.

"I would not want to run as a Republican for president against an incumbent who tried to stop the nonsense." -- Norman Ornstein

But everyone, or almost everyone, and certainly all the political leaders, knew that default was not an option. On many occasions, leaders of the president's party told me that their opposite numbers reassured them privately that if the votes weren't there, the opposition leader would find however many were necessary to change from "no" to "yes" to avoid catastrophe.

This time it has been different. In part, it is because the attitude of Republican leaders is different. Note Mitch McConnell's now famous assertion, repeated multiple times over the past eight months, that his No. 1 goal is to make Barack Obama a one-term president. Cooperating with the president, even on a matter of urgent national need, takes a back seat to the political imperative of making him look bad. Add to that the belief on the part of many Republican lawmakers that their sweeping election victory last November gave them a mandate to take a meat-ax to government, and to roll over the president in the process.

But at least as significant is that, this time, an alternative narrative developed and took hold, that default was no big deal, even desirable, because it would show the world that we were finally serious about reducing or demolishing big government. In the forefront of the no-big-deal caucus was Senator Pat Toomey, the Republican from Pennsylvania, who wrote an influential op-ed in The Wall Street Journal pooh-poohing the dangers, and saying that it would be easy to pay our creditors with the tax revenue rolling in each month.

The G.O.P. presidential candidate Tim Pawlenty weighed in repeatedly in the same vein, noting that we would not only be able to pay our creditors, but the shortfall would starve parts of government -- and what could be bad about that? The influential hedge fund billionaire Stan Druckenmiller reassured the nervous that he would not dump his Treasury bills or demand a higher risk premium, meaning higher interest rates, if default occurred.

End-game negotiations work, and result in an agreement via compromise, when the parties believe that a failure to compromise will lead to disaster for all involved, or at least for those they represent. Take away that belief, and you flirt with disaster.

If the worst happens -- and despite the late-breaking panic among many Republican lawmakers, spurred by an eleventh hour lobbying campaign by business leaders, there is still a significant chance that a deal will fail to take hold, or will be rejected by the House -- who will be blamed? At this point, both polls and logic make it clear that far more voters will blame Republicans than the president or his Democrats.

But let's face it: if the failure results in even a fraction of the negative outcomes most observers foresee, meaning a much deeper setback for an already weak economy, and a serious blow to a struggling global economy, it will hurt the president as well. Anything that happens on his watch becomes a part of his responsibility. Even if we take that as a given, I would not want to run as a Republican for president against an incumbent who tried to stop the nonsense, if I had either contributed to the atmosphere that resulted in a debacle, or stood by silently, with no sense of leadership responsibility, and watched it happen.

Norman Ornstein is a resident scholar at AEI.