"I'd Like To Make A Joke"

This is one weird response.

The NY Times has this:

When asked if he felt that it was more difficult to run against Mr. Obama because of the sensitivities of race, Mr. McCain responded wryly: “I’d like to make a joke, but I can’t.”

What kind of response is that? We have "the sensitivities of race," then a "wry" response, which is that he would like to make a joke, but can't. The "can't" part is no doubt because of past experiences with joking and getting criticism, and maybe some strict advice from his advisers.

But what kind of joke would he like to make? That's the weird part.