I find it pretty hilarious that folks on the left suddenly feel the US is ungovernable, largely because they have not been able to pass a couple of complicated and risky legislative initiatives. Was the US ungovernable when Bush couldn't pass Social Security reform? It seems that showing leadership on a national scale with diverse interests is a tad harder than running a grad school policy round-table. Oddly, the left seems befuddled by actual diversity of opinion, rather than the faux diversity with lock-stepped beliefs they built in academia and among themselves.
I don't read Real Clear Politics much but I thought Jay Cost makes a good point:
Let's acknowledge that governing the United States of America is an extremely difficult task. Intentionally so. When designing our system, the Founders were faced with a dilemma. How to empower a vigorous government without endangering liberty or true republicanism? On the one hand, George III's government was effective at satisfying the will of the sovereign, but that will had become tyrannical. On the other hand, the Articles of Confederation acknowledged the rights of the states, but so much so that the federal government was incapable of solving basic problems.
The solution the country ultimately settled on had five important features: checks and balances so that the branches would police one another; a large republic so that majority sentiment was fleeting and not intensely felt; a Senate where the states would be equal; enumerated congressional powers to limit the scope of governmental authority; and the Bill of Rights to offer extra protection against the government.
The end result was a government that is powerful, but not infinitely so. Additionally, it is schizophrenic. It can do great things when it is of a single mind - but quite often it is not of one mind. So, to govern, our leaders need to build a broad consensus. When there is no such consensus, the most likely outcome is that the government will do nothing.
The President's two major initiatives - cap-and-trade and health care - have failed because there was not a broad consensus to enact them. Our system is heavily biased against such proposals. That's a good thing.
One of the roles of the President is to bring some adult supervision to his party in Congress. Bush failed on this, allowing Republicans to run rampant in earmarking excess, and Obama has if anything been even worse on this dimension. He routinely remains aloof from the legislative details (some would say he just got rolled by Nancy Pelosi) and then proceeds to speak as if the actual bill matches his grand words and promises when it is obvious to all that it does not.