The key question from the second presidential debate is not whether President Obama won. He clearly did, by every measurement. The question is whether it will matter to the trajectory of the race the way the first one did. History indicates that it probably will not; in past elections, far more people have watched the first debate, and had their opinions shaped by it, than any subsequent debates.

Although the president did extremely well last night, probably the best his supporters can hope for is that it freezes the race and stops his precipitous polling slide of the last two weeks. If he accomplished that much, then he is still close enough that he can possibly squeak it out at the end with a really strong closing sprint.

But liberals should not be deluded that last night’s strong performance by the president will undo the horrendous damage he suffered in the first debate. At this point, it is clear that it will be a dogfight for him to win this thing. What, if any, effect his performance last night will have in the polling will probably be clear in a week’s time.