Doug Mataconis and Dave Schuler argue that it really doesn’t matter who gets elected in 2012. Whichever party wins the election, most of the Bush tax cuts will be extended, health-care costs will continue to rise, Guantanamo will remain open, the homeland security apparatus will expand, Congress will remain gridlocked, the president will continue to claim extraordinary powers to prosecute ‘the War on Terror,’ etc.

(Bill O'Leary/The Washington Post)

I toy with this sort of argument myself. But I think the beginning of wisdom on this point is to recognize that the differences between the two parties are largely swallowed in congressional gridlock. The issue here isn’t that Mitt Romney and Barack Obama wouldn’t like to govern very differently. Obama, for instance, would very much like to pass a cap-and-trade plan to regulate carbon followed by an immigration-reform bill that included a path to citizenship. Romney would not like to pass those laws.

But, on most issues, “governing” means “passing legislation through Congress.” And quite often, Congress can’t govern at all. The two parties don’t so much end up agreeing as end up failing to resolve their disagreements. The result is drift.

At least, that’s been the case for the last year or two. But if Romney wins, he’s likely to have a Republican House and Senate. His majorities may not be large, but much of what Republicans want to do — say, all of the Ryan budget — can be passed through budget reconciliation, which would make Democratic filibusters ineffectual. So it’s possible to imagine dramatic legislative change in the first year of a Romney administration.

With Obama, how much can get done depends on how you think Republicans will react to a loss. There’s a $7 trillion fiscal cliff coming at the end of 2012, and if Republicans have failed to win back the presidency and have to resign themselves to four more years of Obama, there may be a number of them who decide that they may as well get some governing done before attention turns to the midterm election. Or, conversely, they could be so angry over the loss that they’re even less willing to cooperate.

Which is all to say that though we spend most of our time talking about who gets elected to the presidency, it matters quite a bit who gets elected to Congress in 2012, and what they think their election meant. The presidential race gets all the attention, but it’s the composition of the Congress that decides, in many cases, what the president can actually do.

Or, to put it slightly differently, I think it’s an open question whether a political party should prefer to control Congress or control the presidency. And if we’re talking about filibuster-proof control of Congress, I’m not even sure it’s close.

(Obvious disclaimer: There are a lot of places where the president has considerable leeway, from regulations to Supreme Court nominees to how to respond to foreign crises, and in those cases, the differences between the two parties tend to be both considerable and actionable without a functional majority in Congress.)