Having one-party control of both houses of Congress and the White House may allow national action to be taken more quickly, but it's contrary to the spirit of our system of government. The Founding Fathers explicitly rejected a parliamentary arrangement, in which the executive and legislative branches are united under the same party. Not only did they separate the legislative and executive functions; they further divided the legislative function into two bodies with different numbers, different terms of service and different election methods. (Remember that prior to the 17th Amendment, senators were elected by state legislatures.)
In short, divided government was baked in the cake by the Founding Fathers, who wanted lawmaking to be slow and difficult, not quick and easy. They reasoned, wisely, that laws able to overcome their institutional obstacle course were more likely to be clearly considered, broadly supported and equipped to stand the test of time.
Reagan had to contend with a Democrat-controlled House of Representatives for all eight years of his presidency. This was no barrier to genuinely popular legislation, such as the 1981 tax cut. The White House simply had to work harder and make better arguments for its program. And Democratic control of the House helped make the 1986 Tax Reform Act one of the few major tax bills in history to which both Republicans and Democrats still point with pride. Similarly, Bill Clinton faced divided government for six of his eight years, and those years gave us the 1996 welfare-reform bill, which continues to have broad support.
These laws endured because they had legitimacy. It's unlikely that either party would single-handedly have produced anything as good. Indeed, one-party government encourages the majority to pass legislation using votes only from its own side and usually leads it to bargain first with those on its own extremes (those least willing to compromise on anything) instead of moderates across the aisle. This almost guarantees that controversial lawmaking will be the norm.
Divided government has other advantages, too. For one, it restrains government spending. The budget surpluses of the late 1990s resulted mainly from Bill Clinton's unwillingness to support the Republican Congress's priorities -- and its unwillingness to support his. For another, it improves our foreign policy. We had divided government during 36 of 55 years between 1947 and 2001, which meant that both parties had to take responsibility for the wars in Korea, Vietnam and Iraq (the first one). America is much more effective in the international arena when it has a high degree of bipartisanship in its foreign policy. In the not-too-distant past, Republicans including Arthur Vandenberg and Democrats including Daniel Patrick Moynihan understood this. With the current war in Iraq, however, Democrats who support the war are forced to oppose it, and Republicans who oppose the war are forced to support it. This makes other countries unsure of our resolve and commitments.
Those who worry that divided government would compromise our efforts in Iraq shouldn't be overly concerned. As the minority party, Democrats today are free to criticize our efforts in Iraq without having to offer constructive alternatives. But put them in the majority, and they'll suddenly have to put up or shut up. Let them defund the war and implement an immediate pullout if that's what they really think we should do. At least it would force the administration to explain itself better and face some oversight, for which the Republican Congress has essentially abrogated all responsibility. Polls will quickly indicate which side has made the better case.
Finally, on a purely partisan level, I believe that loss of one or both houses will strengthen the Republican Party going into 2008. It will force a debate on issues that have been swept under the rug, such as out-of-control government spending and the coziness between Republicans and K Street, home of Washington's lobbying community. Afterwards, the party will emerge stronger, with better arguments for keeping control of the White House. Also, Democrats may well be placed under so much pressure from their left-wing fringe that they'll be forced into politically self-destructive acts such as trying to impeach President Bush.
Every Republican I know thinks Nancy Pelosi and Harry Reid are the best things they have going for them. Giving these inept leaders higher profiles would be a gift to conservatives everywhere.
Bruce Bartlett is the author of Impostor: How George W. Bush
Bankrupted America and Betrayed the Reagan Legacy. This essay first appeared in the Washington Monthly.