50 the magic number for Obama

As a pollster, I spend half my time telling people there are no magic numbers. There is no job performance or favorability rating above which victory is inevitable and below which defeat is certain.

I tell people I live in a world of probabilities. Typically those probabilities seem to rise and fall in a fairly linear way. The higher your job rating, the less likely you are to lose.

Yet there are some magic numbers in our world. Though I didn’t appreciate its significance at the time, we all learned about one magic number in elementary school —32 degrees. Change its temperature by a vast 178 degrees, from 211 to 33 degrees, and water is just, well, water. It may go from being hot water to cold water, but it is still water.

Alter its temperature by just 1 degree, however, as long as it’s from 33 to 32, and water changes radically, transforming from a liquid to a solid — ice. Thirty-two degrees seems like a magic number after all.

Other magic numbers are less well-known, perhaps even incalculable, but nonetheless evident. Again, I didn’t appreciate its meaning at the time, but I learned about another magic number in the sandbox, though I can’t tell you what it is. I’d build a sand pile and then add one grain at a time until all of a sudden the pile collapsed or shifted in some dramatic fashion. Thousands of grains of sand seemingly made no difference, and then, suddenly, just one altered the fundamental shape of my little mountain.

Physicists call systems with these characteristics “complex” — the magnitude of effects are unrelated to the magnitude of causes. One small movement can make all the difference.

Is politics a complex system? I can’t say for sure. But perhaps there are some magic numbers after all.

Take the effect of presidential approval on midterms. We graph the relationship between a president’s approval rating and his party’s gains and losses in midterm elections, thinking of the result as a smooth relationship. The lower the president’s approval rating, the more seats his party loses.

But the pattern is not really so linear after all. There is a sharp discontinuity at 50 percent. Presidents whose approval rating is at 50 percent or above have lost, on average, just 11 seats in the House, while presidents under the 50 percent mark have lost an average of 33 seats.

Averages can obscure as much as they reveal, so pick apart the numbers. No president with an approval rating under 50 percent has lost fewer than 15 seats. The next smallest number is 26. Even a president just below 50 percent can lose a lot. When Democrats were punished with the loss of 52 House seats in 1994, President Clinton’s approval rating rested just under the 50 percent threshold, at 48.

Only one elected president with an approval rating above 50 suffered massive losses — Eisenhower in 1958. Interestingly, the country was mired in a recession so deep that only once between the end of World War II and our current slowdown did GNP decline by more than it did in 1958, yet voters had trouble blaming the general who had won the war. They had no trouble blaming his party.

Next to that debacle, the biggest loss for a president over 50 percent was 18 seats, and next to that just 12. Two presidents with approval ratings above 50 percent actually gained seats in midterms.

So where does President Obama stand? Last week Gallup put his approval at 45 percent, this week at 49. The Pollster.com weighted average of all polls says 46 percent. In short, for now, the president is hovering just below what may prove to be a magic number for Democrats in 2010.

Mellman is president of The Mellman Group and has worked for Democratic candidates and causes since 1982. Current clients include the majority leaders of both the House and Senate.