I came across this posting via Jim Grey’s Recommended Reading column for today. He linked to John Scalzi’s post entitled “But What if We Didn’t?” – and that has cleared the confusion as to why the American Congress has gone from attempting to work together to tearing each other apart.

When Ronald Reagan was President, he and Tip O’Neillc ould get along.
Now?
I will leave you to ponder what Scalzi writes – and strongly suggest you Scalzi’s post in its entirety by clicking on the link above or anywhere on the quotation below:
I have a theory about the Republican Party, and it is that around the time Newt Gingrich became the head of its brain trust, the GOP added a fourth functioning principle to its previous tripod of “Southern Strategy to corner the racist vote,” “Abortion to corner the Evangelical vote” and “Tax cuts to corner the capitalist vote (and money).” The fourth principle was not about kettling and controlling a voting bloc, but rather a principle to maximize its power and to motivate the voting blocs beyond whatever the GOP could offer them politically.
That fourth principle, to put it in its shortest and bluntest form, is:
“But what if we… didn’t?”
Somewhat more broadly, the Republicans recognized there was a suite of political conventions and traditions that were designed to make it easier for things to get done, and that this suite of conventions and traditions were exploitable by denial. While people in both parties (and the parties themselves) would occasionally use this exploit, it was not done systematically.