Forget what President Barack Obama and Mitt Romney say they want to do next year. The better question might be: How do they intend to get any of it done? To use a phrase that was popular during the Democratic primary in 2008, what’s their “theory of change”?

One common theory is that the two parties are so far apart that this election, finally, will provide a mandate for the winner and shock the losing side into cooperating. “We’re going to have as stark a contrast as we’ve seen in a very long time between the two candidates,” Obama told donors in Minneapolis. “My hope, my expectation, is that after the election, now that it turns out that the goal of beating Obama doesn’t make much sense because I’m not running again, that we can start getting some cooperation again.”

Representative Paul Ryan, speaking at the Reagan Library, was even more emphatic: “If we make the case effectively and win this November, then we will have the moral authority to enact the kind of fundamental reforms America has not seen since Ronald Reagan’s first year.”

This is conventional wisdom. Elections are arguments about where the country should go next. The candidate who wins the election wins the argument. The opposition party, disappointed as they may be, has little choice but to step aside. After all, they’re out of power.

But can you remember the last time it actually worked that way? The U.S. political system makes winning an election a necessary but very insufficient qualification for governing. The frequent elections in the House and staggered elections in the Senate, the expansion of the filibuster, the influence of the Supreme Court and the polarization of the political parties combine to constrain power. You can win an election and quickly find you lack the support to pass major priorities. Recall President Bill Clinton being stymied on health-care reform, or President George W. Bush’s failed run at Social Security privatization.

Mandate Mechanics

If you consider the mechanics of presidential mandates, it’s clear why they don’t amount to much. For one thing, contemporary elections are decided by narrow margins. Had 3.6 percent of the electorate voted the other way in 2008, Senator John McCain would be president. In 2004, if 1.25 percent of Bush’s voters had switched sides, Senator John Kerry would have won. In 2000, well, the winner didn’t even win the popular vote. In 1992 and 1996, Clinton won majorities in the Electoral College, but due to Ross Perot’s popularity, he never won the majority of the popular vote. None of these elections produced the kind of Rooseveltian or Reaganite landslides that cow the opposing party into submission.

Nor is it clear what specific policies voters have endorsed when they select a president. Although some go to the ballot box having read every word of their chosen candidate’s agenda, most don’t. A swing voter in Ohio might turn against Romney because of his links to Bain Capital LLC without intending to endorse Obama’s ideas on immigration reform. “In short,” wrote political scientist John Sides in a roundup of academic research on presidential mandates, “we cannot interpret an election outcome as a wholesale endorsement of the winner’s policy proposals (or as a wholesale rejection of the loser’s).”

In addition, members of Congress don’t report to a national electorate. They report to their state or district. If Obama narrowly wins the election but badly loses Kentucky, is Senate minority leader Mitch McConnell really betraying the will of the people in organizing relentless opposition to Obama’s policies? McConnell’s certainly not betraying the will of his people.

Worse, members of Congress — particularly Republicans — increasingly fear their primary election opponents more than their general election opponents. If you’re a Republican in a reliably Republican district or state, you’re probably more likely to lose to a far-right primary challenger than to a Democrat. (Just ask Bob Bennett, the former senator of Utah, or Richard Lugar, who just lost the Republican Senate primary in Indiana.) As a result, the voters you’re most eager to assuage aren’t just Republicans, but hard core conservatives. They definitely don’t want you standing down out of obeisance to some abstract notion of “mandates.”

Next Election

Finally, when a party does lose an election, it turns its attention to regaining power in the next election. In Robert Draper’s book “Do Not Ask What Good We Do: Inside the U.S. House of Representatives,” he reports on a strategy dinner attended by top Republicans, including Eric Cantor, Jim DeMint, Kevin McCarthy and Ryan, on the eve of Obama’s inauguration. “If you act like you’re the minority, you’re going to stay in the minority,” Draper quotes McCarthy saying. “We’ve gotta challenge them on every single bill and challenge them on every single campaign.”

McCarthy, of course, was right. Minorities don’t become majorities by helping the other party govern successfully. When things go well, voters reward the party in charge. More often, minorities become majorities by grinding the gears of government to a halt, amping up partisanship and doing everything they can to make sure voters are disgusted with Washington. Given such incentives, the belief that minority politicians will clap their majority colleagues on the back, mutter “good game,” and get out of the way is fantasy.

There is one theory of change that works even in an age of intense polarization: having the votes to pass your agenda. Obama learned this when the Senate approved health-care reform with zero Republican votes. Ryan talks about the “moral authority” to enact fundamental reforms, but if his budget passes, it will do so because Republicans gain control of both chambers of Congress, and budgets can’t be filibustered in the Senate. Obama, who is likely to face a divided Congress if he’s re-elected, will have to hope that the expiration of the Bush tax cuts and the “trigger” of the spending sequester give him sufficient leverage to force Republicans to work with him.

Fiscal policy is a special case in which the consequences of gridlock will make action necessary and Senate rules make passage easier. On most issues, neither Obama nor Romney is likely to have the votes or cross-party cooperation to get much done. Washington is too bitterly polarized for that, and the U.S. political system is too easy to stymie. If voters don’t like that state of affairs — if we want elections to produce leaders who can govern effectively — then the question, really, is what our theory of change is. Because simply turning Democrats and Republicans in and out of office doesn’t seem to be working.

Ezra Klein

Follow Ezra on Twitter @ezraklein. Ezra Klein is the founder and editor-in-chief of