Over the last few days, a couple videos have come out contrastign John McCain's efforts to cast himself as a moderate against his previous efforts to cast himself as a conservative die-hard. Here's McCain embracing, and then distancing himself from, President Bush:

And here he is on privatizing Social Security:

What makes these videos so devastating is that they simultaneously undermine his two most vital political assets: his reputation as an unwavering straight-talker, and his reputation as a moderate. If deployed correctly, these videos ought to be at least as damaging as John Kerry saying he voted for the $87 billion before he voted against it.

And for all I know there could be more to come. Because McCain strayed so far from the GOP line from 2000 through 2004, in recent years he has had to tie himself to party dogma more explicitly than other candidates. A conventional conservative Republican wouldn't have had to repeatedly assure audiences that he wanted to privatize Social Security and agreed with President Bush on nearly everything.

McCain is in the last stage of an extremely tricky balancing act. First he moved far to the left and nearly deserted the GOP (that was the new McCain). Then he had to move back to the right and win the Republican nomination (the New New McCain)-- and he succeeded, though it required a lot of luck. Now he has to move back to the center again (The New New New McCain), but do so without compromising his most precious attribute of straight-talkiness. Meanwhile, because he's so accessible, every iteration of his evolution is on video. Now, he has a lot of leeway precisely because he has such a strong reputation for upholding his principle, but even so this is going to be tricky.

--Jonathan Chait