Obi-Wan reappeared briefly to answer my question about why so many liberal readers get furious when I highlight polling data showing that Obama’s not running away with the race…

“Why are they angry? Because their whole strategy relies on a demoralized GOP. Remember the scare they had in September?” Obi-Wan asked. “All that coronation stuff at the Democratic convention dissolved as McCain seized and held a good lead. They know how fragile things are. They need to keep the media talking about a massive GOP defeat, because all it might take is a few stories to the contrary and all of a sudden, it is mid-September again, when the rising McCain tide was lifting all boats.”

I went back to look at that “scare in September.”

On September 2 — when the polls were reflecting the Biden pick and the Democratic convention, but probably not yet the Palin pick of three days earlier – the RealClearPolitics average was at 49.2 percent for Obama to 42.8 percent for McCain — a 6.4 percent lead for Obama.

On September 8, five days after Palin’s convention speech, the RCP average put McCain at 48.3 percent to Obama at 45.4 percent — a McCain lead of 2.9 percent.

That amounts to a swing of 9.3 percent in six days.

Now, since then, Obama has turned in three debate performances that probably reassure a lot of voters, and so his lead is probably more solid than his lead on September 2. And we’re basically comparing post-convention bumps; September 2 should have been one of Obama’s best days, and September 8 should have been one of McCain’s best days.

But that 9 percent swing does suggest that things can change in a hurry…