The Wiki page on Tom Lehrer says he lost interest in writing political satire back in the 60s.
Maybe he just ran out of material.
Remember this one?
Something about this post makes me think of it. Maybe it's the CNN "poll" (in the video at the link), which asks:
Are you concerned that President Obama seems compelled to continue to apologize for the United States wherever he travels?I'd like to suggest a poll topic for next time: "Are you aware of the term 'leading question'?"