Campaign Status page): Bachmann, Cain, Gingrich, Huntsman, Paul, Pawlenty, Romney, and Santorum. Each of these candidates have attended at least one previous debate, except for Jon Huntsman. The former governor of New Mexico, Gary Johnson, was not invited to attend; he may well find himself excluded from the remaining debates.
Since this is Huntsman's first debate appearance, it will give him an opportunity to make a good--or bad--first impression. First impressions in debates can be useful; Michele Bachmann and Herman Cain each boosted their visibility and popularity following their initial debate performances. Most people have never seen or heard Huntsman, so he will have the task of introducing himself to the public on a solid footing. But it may be difficult for him to get attention, given how many players are on the stage.
Tomorrow's debate will be at an awkward time in the race: Most watchers' eyes are on Rick Perry, who is poised to enter the race. But as Elephant Watcher predicted back in June, Perry will enter the race immediately after the debate and the Ames straw poll, in order to blunt their impact. Thus, Perry will be on everyone's mind, but he won't be present. This may give the impression that the debate (and Ames straw poll) are sort of a waste of time.
There are a few things to watch for, however. Tim Pawlenty's criticism of Bachmann in recent weeks may encourage the debate moderators to stoke a fight between the two. Sarah Palin appears to have dropped off the radar entirely, so a new "feud" will need to be developed. Pawlenty is in a difficult position: He stands to lose much and gain little by attacking Bachmann, but because he refused to attack Mitt Romney during the June debate, he will be tagged as a timid candidate if he runs from another fight.
Meanwhile, both Newt Gingrich and Herman Cain will need to make full use of their debate platforms to re-energize their campaigns and get media attention. Otherwise, they'll descend from the field of view. Romney, on the other hand, will attempt to stay above the fray. The big question for Romney will be whether he is forced to address the Romneycare issue more fully, or if he gets another pass.