He criticized McCain on Glenn Beck's program as well:
Fred Thompson - January 15th, 2008
GLENN: But he’s also wrong with McCain/Lieberman where he wants to sign treaties for global warming. He wants to give away sovereignty on global warming. This guy is not a conservative.
SENATOR THOMPSON: No, I think he’s in the wrong direction on that, too. I think that that’s absolutely true. But, you know, he’s like everybody else. You know, he has his strong suits and his weak suits.
Definitely a critical assessment (there's a bit more after the selected quote), but fairly measured considering that the two of them are, in fact, opponents. The fact that it's considered news that one primary candidate is actually criticizing another just goes to show how civil Thompson's been to McCain to this point.
Still, I find it far more interesting that he continually refuses to really lay into McCain. Later in the Beck interview, for example, he responds to Beck berating McCain further by shifting the attention to Giuliani.
What's most interesting about this, though, is that it indicates a genuine effort on Thompson's part. If he'd more or less accepted defeat, I suspect he'd go after Huckabee, go for a strong showing in South Carolina, and probably find himself on the short list for VP, or maybe AG. But he's talking like he wants to win South Carolina, which obviously necessitates going after the front-runner, at least somewhat.
In Punditish's opinion, though, Fred's still holding back. That might change if his rise in the polls continues.