I think the answer depends on how aggressive the chip leader is.
If they are a very aggressive player, and catching cards, then the hot streak will end and you need to be ready to pounce. Tighten up against the CL, and when you get a hand, let them bet into you, raise them up and hope to double.
If they've just gotten to the CL and then change their strategy by tightening up & coasting, then raise, raise, raise. Push the situation and take pots that you wouldn't normally.
Point is - every CL is different and you have to adapt to be successful. But I definitely agree that the only way to win at tournament poker is to take down the one at the top.