On Election Day, Joe Biden had some fun with the press by hinting that he’s going to run for president in 2016. I have no idea whether there’s anything to it. But if he’s smart, he’ll keep up the pretense for a while at least. Why? Because it will help Barack Obama be a better second-term president.

As everyone knows, second-term presidents have repeatedly run into trouble. This was often the case before the 22nd Amendment turned them all into lame ducks; even Franklin Roosevelt had plenty of second-term troubles. However, it’s almost certainly better for a White House to be focused on keeping constituents happy at the next election than for the president to worry about his legacy, or to be otherwise preoccupied with the things he couldn’t do when he had to worry about voters.

The problem the reason the presidency works — when it does — isn’t because we elect citizens to that office who have particularly wise insights into good public policy. Good presidents, from FDR, Lincoln and Washington on down, are good because they are good politicians. That means, more than anything, that they’re good at representation.

But representation is a process; as the political scientist Richard Fenno tells us, it involves a cycle of making promises during a campaign and governing with those intensions in mind, explaining actions in office in terms of those promises, and then returning to the campaign trail to make the cycle start all over again. Without an upcoming election, that process doesn’t work right. And politicians may well be tempted to substitute their own preferences for whatever they promised during their campaigns.

Campaign promises at their best, whether on policy or style, don’t come out of arbitrary guesses by politicians, or even simply out of whatever works in focus groups. Instead, campaign promises are policy positions worked out in negotiations (either explicit or implicit) with organized groups; they are policy commitments that, in some way, make sense. They’re connected to the candidate’s constituents.

So take away the next election, and politicians may be tempted to do whatever they want, and that leads to all sorts of dangers.

Having a vice president interested in the top job is no guarantee that presidents will avoid that problem; after all, George H.W. Bush was running hard for the White House when Iran-contra almost ruined Ronald Reagan’s presidency. But having someone within the administration who deeply cares about how things will look in November of the president’s last year in office — and who deeply cares about how things will look to party actors throughout the president’s last term — can only help.

I have no idea whether Biden is really going to run or not, but either way, he should act like he is for as long as he can get away with it — and I’d advise Obama to govern as if what he really cared about was securing a third term for the administration through Biden.