Jonathan Martin had an interesting piece up yesterday about the floundering Thompson campaign. He's got lots of good detail in there and it's well worth your time. My only quibble is that he's a little too generous to Thompson. (Having written this genre of piece myself, I suspect he's worried he was too hard on the guy, if anything. I would have probably written it the same way...)
For example, after a long and unflattering lede, J-Mart writes, "But Thompson soldiers on, and he is sure to be a factor in a contest so uncertain that no less than six candidates could play a significant role in deciding the outcome." I disagree. While it's possible that Thompson will be a factor in the race--he could edge out Giuliani for third in Iowa, which would damage the ostensible frontrunner--I think it's far from a sure thing. Particularly once you get beyond Iowa. According to Pollster.com, Thompson is running second in South Carolina, behind Giuliani and less than a point ahead of the surging Romney. He's also got the steepest downward trajectory there of any candidate. In Thompson's other must-win state of Florida, he's taken a precipitous nose-dive (down about 8 points in the last six weeks), putting him almost 20 points behind Giuliani in the state and three points back of the (once-again) surging Romney. Given the problems with organization and motivation that J-Mart highlights, it's hard to imagine these trends reversing themselves. Especially if Romney wins Iowa and New Hampshire, at which point I'm not sure even a highly-motivated, well-disciplined candidate will be able to stop him.
(One scenario in which Thompson becomes a serious player: Romney wins those two early states, Giuliani falters badly there, Huckabee never gains traction outside Iowa, and the McCain comeback fizzles with a third-or-worse showing in New Hampshire. Then, if Thompson has somehow managed to get up for third in Iowa, maybe he becomes the anti-Romney in the South. But it seems almost too remote a possibility to consider.)
Also, don't forget that negative momentum tends to reinforce itself: Backsliding in polls leads to lower fundraising and ship-jumping supporters, which leads to lower poll numbers, etc., etc.