The Bush hit on Rubio was obviously premeditated, so it wasn’t gaffe or a mistake. It was a revealing measure of his political talent and judgment. Let’s count the ways in which it was strategically ill-conceived and tactically incompetent:
1) He attacked Rubio not from a position of strength, but of weakness. “I’m a constituent and you’re not doing your job for me” is the personal complaint of a whiner. He looked like a disgruntled employee, not a leader.
2) He attacked Rubio on grounds of procedure and not substance. However important they might be, no one actually cares about voting absentee rates—the same way they don’t care about filibuster rules or the nuclear option. To think that this was the angle to blow up Rubio is insane.
3) As I said, Bush’s attack was almost certainly a pre-meditated set piece. Yet he didn’t have the political sense to see that Rubio was in a very good frame coming off of an answer where he beat the snot out of the moderators. Bush had no ability to read the scene and understand that it would have been better in that moment not to take the shot. He had a plan, so he robotically stuck to it.