Of course, conservatives who dislike President Obama’s policies can be expected to trumpet the news that his poll numbers appear to be falling. But you don’t have to be an Obama critic to recognize that a decline in public support for the president can have a significant impact. Witness John Sides’ analysis for The Monkey Cage blog.

First, it matters for the 2014 election. A simple model of House election outcomes constructed by political scientist Gary Jacobson shows that the share of seats controlled by the president’s party depends in part on presidential approval. You can see some discussion of that in Jacobson’s post-mortem on the 2010 election. Obviously, other factors matter too. But a less popular president certainly provides headwinds for Democratic candidates.

Second, it matters for the 2016 election. Of course, that’s a long way away, and a lot can happen between now and then. But again, simple forecasting models show that, controlling for other factors, the incumbent party does better when the incumbent president is popular. (See, for example, what Lynn Vavreck and I report in Chapter 2 of The Gamble.) Approval appears to matter more when the incumbent president is running for reelection, but it still appears to matter even when that president is not running. Let’s quantify that. I estimated a model of presidential election outcomes from 1948-2012 that included change in gross domestic product over the first two quarters of the election year, presidential approval as of June of the election year, an indicator for whether the incumbent is running, and the interaction of approval and incumbency. This model suggests that when the incumbent is not running, a 7-point drop in approval is associated with a 1-point drop in the incumbent party candidate’s share of the major-party vote. If I were Hillary Clinton or any other Democratic hopeful, I’d want Obama to be as popular as possible when he leaves office. And if I were Obama and I wanted the legislative achievements of my presidency to last, I’d want a Democrat to win in 2016.

Third, it matters for whether the President gets what he wants from Congress—with some caveats. Here’s a sense of some of the scholarly literature on the relationship between presidential approval and legislative success. One question is whether Congress simply passes legislation that the president supports. In one study (gated) of 208 roll call votes in the House between 1989-2000, political scientists Brandice Canes-Wrone and Scott de Marchi found the House was more likely to do what the president wanted when the president was more popular. This effect was only significant among legislation that was both salient (mentioned a lot in news coverage) and somewhat complex (focusing on regulatory matters in particular). But, of course, that’s exactly the kind of legislation—e.g., immigration, gun control—that Obama would like to sign right now.