It's not clear who is responsible for the gridlock in Washington. No doubt there is blame for all involved -- House, Senate, President, Republicans, and Democrats. From my point of view, however, the main culprit is the Republican minority in the Senate. This is because they are thwarting the will of the Democratic majority. They are using parliamentary tricks, mainly the filibuster, to block majority rule, which I think goes against the Constitution. If the Constitution wanted to require a 60% majority to pass any legislation in the Senate, it would have said so. It already says that it requires a two-thirds majority to start the process to amend the Constitution. It could have spelled out other times when a super majority was required; the fact that it did not, indicates that the founding fathers did not intend to require a super majority for conducting the ordinary business of the Senate.
The Senate has imposed this new super majority requirement on itself. The Democrats and the Republicans have both used it, but the Republicans have used it much more than the Democrats.
The Republican use of he filibuster super majority bodes ill for the "fiscal cliff." The Republicans can block any attempt to resolve the crisis that they do not like. In a recent "60 Minutes" interview, Mitch McConnell indicated that he was not inclined to compromise. He said that what the Democrats were doing in terms of running up debt, etc., was bad, and he would try to stop it. That may be, but the problem is that doing nothing may be worse than doing what the Democrats want. McConnell can try to limit tax increases and expand budget cuts, but that requires some kind of compromise. If he lets the nation slide off the fiscal cliff, very few will benefit. His extremely wealthy friends and supporters will suffer less than most; some will probably figure out how to make money from the disaster, but most people will suffer. He is very short sighted to destroy America just to enrich a few of his friends and supporters.