Cenk Uygur has a theory about why this is happening to Rush right now:
But one thing is for sure — he’s hurt, dog! That’s why we see the unprecedented apology from him on Sandra Fluke. When this controversy first broke, I predicted on our show that more advertisers would drop him (at the time, only two had). Advertisers are much more likely to drop a controversial guy if his numbers are already down. They’ll ride it out if he’s still delivering the goods. This is the same thing that happened to Imus. His ratings were miserable already, so advertisers didn’t have enough incentive to stick with him when trouble arose.