It's often argued that a divided government — where one party controls Congress and the other controls the White House — results in more balanced, centrist governance than that of a united government. In other words, by turning on both the hot and cold water faucets in the federal bathtub, we can all bathe in water of a pleasing temperature.
Divided government doesn't ensure good government, but it may limit bad government by checking the worst instincts of both parties.
I'm sympathetic to the principle, but it's a principle that sounds a lot cleaner and loftier as an abstract term than it ends up being in the dirty politics of real life. A better metaphor might be two equally matched teams trapped in a tug-of-war stalemate.
Take for example the recent confirmation of Elizabeth Duke to the Federal Reserve Board (also posted about by Amber). The seat had been vacant for a long time, and it's only after extended wrangling between the Senate and the White House that a compromise was reached and anything was done. This isn't uncommon. Towards the end of 2007, NPR and other media were full of stories of relatively non-political government agencies and domestic safety programs underfunded and unable to adequately plan their next fiscal year because the Federal budget was so delayed because of just this sort of stalemate.
Maybe Congress is to blame. Maybe the White House is. But it doesn't matter. The fact that the Fed is non-partisan and yet nothing got done for so long is exactly the point — divided government may prevent bad governance, but it too often prevents any governance at all.
In any major undertaking, professional or political, participants should disagree. They should call out each other's bullshit. They should question each other's assumptions. But all of this requires a constructive working relationship, and if a private company's leadership had relationships as dysfunctional as our federal government does, the company would have been out of business a long time ago.
Of course, whether or not you actually agree with what gets done in a united government is a completely different question. But if you want a divided government, you have be willing to put up with the mess.