In May 2001, I wrote an op-ed for the Washington Post in the wake of Vermont Sen. James Jeffords' party switch. I argued that the switch, which cost Republicans control of the Senate, could well turn out to be good for President George W. Bush.
Though not entirely for the reasons I speculated on in the op-ed, I turned out to be right.
Bush was still able to get enough cooperation to govern over the next year and a half, and he was also able to run successfully against the Democratic Senate in the fall of 2002. The GOP regained control that November.