By Ken Tucker
Updated November 23, 2011 at 02:52 PM EST

If there was one overriding theme of last night’s Republican debate on CNN, it wasn’t so much the stated theme — national security — as it was the underlying one: These candidates are now, for the most part, conforming to the images the news media has imposed upon them.

Newt Gingrich? He’s officially on the rise… this week. His poll numbers are up, and last night, his command of rhetoric was assured. His takeaway line — that military budget cuts were reasonable because “If it takes 15 to 20 years to build a weapons system when Apple changes technology every nine months, there’s something profoundly wrong with the system” — went over well with the audience. His sniffy condescension act plays as superior intelligence in the right setting, and this was the right setting for him.

Herman Cain? He’s officially on a downward slope. His poll numbers are sinking, mostly because he’s giving off the sense that he’s not quite in command of facts. He’s relied upon the “I’d consult the experts” answer too frequently; way too frequently last night. It’s one thing to position yourself as “a businessman, not a politician,” but at some point, the businessman has to morph into a national leader, and Cain isn’t giving off that vibe. That, and the fact that he gave late-night comics another easy punchline, referring to debate moderator Wolf Blitzer as “Blitz,” then hastily saying of course he knew the anchor’s name was “Wolf,” that it was a joke — a joke, he tells you!

Michele Bachmann? At this point, one almost feels sorry for her. Her image as the former front-runner whose dips into extremism have gotten her the sexist crazy-lady label obscure whatever solid points she made. She didn’t help herself last night when she trotted out her glib line that the CIA is run by the ACLU when it comes to interrogation. This sort of thing obliterated the fact that her retort to Rick Perry about Pakistan (that we should exchange intelligence information with other countries and engage with Pakistan to monitor the country, not cut ourselves off from it) was direct and sensible.

And so it went. The challenge for most of the candidates currently is overcoming the images the media is trying to impose upon them, to get a fresh wind behind their campaigns and alter “the narrative,” as the pundits wearyingly put it.

Did you watch the debate?

Twitter: @kentucker