Sean Trende has an important column that connects presidential job approval to reelection results. You really should read the whole thing, but here is the big take home point:
[I]ncumbent elections have historically looked more like referenda than choices, and so far, this election is looking like one as well. Voters who approve of the incumbent largely vote for him; those that do not approve of the incumbent vote for the challenger, except in extreme circumstances.
This is exactly right, and something I have been discussing for some time now. It also points to why I think the conventional wisdom of President Obama being a heavy favorite for reelection is massively oversold.
In fact, I’d argue that he is an underdog. For a simple reason: A majority of Americans do not think Obama is doing a good job, and they have thought that for a very long time.
Now, let’s be clear. It is not an overwhelming majority of Americans, not by any stretch. We are not in Nixon ’74, Carter ’79, or Bush ’08 territory with Obama. However, we have seen a durable 50-55 percent of Americans either disapprove or at least not approve of his job performance for quite a while.
To appreciate this, consider the following picture, which tracks Obama’s job approval in the RealClearPolitics average, from the beginning of his term through the end of 2009.
The president entered office with enormous public support, which he retained even after the relatively controversial stimulus bill. It was only when the health care debate started to heat up – between Memorial Day and Labor Day – that his numbers fell. And boy did they fall. On June 1, 2009 his net approval was a solid +28.2, but by September 1 it was at +7.8.
The most noteworthy decline in 2009 occurred among independents. We can appreciate that when we take a look at the Gallup poll numbers from 2009. Gallup helpfully breaks down its approval data by party identification, and the numbers are illuminating.
Obama started losing GOP support with the stimulus, but independent voters held with him through about the 20th week of his first year. They started breaking against him around Memorial Day, and by the end of his first year in office his job approval with independents had dropped a solid 15 points.
You’ll note that Democrats by and large stayed with the president in 2009, and they have continued to do so. As the core Democratic voting coalition is roughly 45 percent (not since 1984 has the party carried less than that in the two-party vote for any national election, House, or presidency), Obama’s job approval has not dropped out of the mid-40s for very long.
But he has never won independents back, at least not for a sustained period of time. That is why, over the last two years, his job approval has mostly been stuck in a very narrow range in the mid-40s, as the following chart from RealClearPolitics of his job approval from 2010-present makes clear.