Only a handful of modern elections have not had an incumbent president on the ballot. In these contests, the president’s approval ratings are unsurprisingly less important than when a president is running for re-election. So Mr. Obama’s approval ratings will matter in 2016, but it is hard to say exactly how much.

The balance of evidence suggests that the break-even point for the presidential party’s odds of victory is at or nearly 50 percent approval. If the only thing you knew about the 2016 election was Mr. Obama’s approval rating on Election Day, you might guess that the Democrats had a 37 percent chance of holding the White House with a 46 percent rating — rather than a 23 percent chance with a 41 percent rating. The difference between 41 and 46 might be worth between one and two percentage points to the Democratic candidate in 2016 — the difference between a close race and a modest but clear Republican victory.

Mr. Obama’s surge among Hispanic voters might be particularly telling. It is a sign that Democratic-leaning voters dissatisfied with Mr. Obama’s performance might not be so disillusioned that they can’t be lured back to the Democrats by the issues and messages that brought them to the party in the first place. The president’s ratings among liberals and Democrats remain mediocre — perhaps only in the low 70s and low 80s, respectively — suggesting that there are additional, low-hanging opportunities for Mr. Obama and his party’s next nominee.

Of course, there’s a long time between now and 2016. Mr. Obama’s ratings could continue to climb with sustained economic growth; they might relapse with another round of bad news. But the modest improvement in Mr. Obama’s standing suggests that the Republicans cannot count on an easy midterm-like victory if the economy continues to grow at a healthy pace.