It's never been about the size of Limbaugh's
audience.
He's a propaganda mouthpiece. There has never been any independent confirmation of his claim that he has an audience of 20 Million listeners a week.
He is critical to the Repukes, because he has enough of an audience to infest America. It could be just a few million, but they are like Pod People.
We've all seen them. They're the ones that show up at the local PTA meeting and waste everyones time with some "drivel" they've heard from Rush. They're in the line behind you in the Grocery Store, offering their "absolutely unfallable" opinion of all that is wrong with America. They're the guy at Little League who argues for half-an-hour over whether you can have a girl on the team.
The Repukes can't and won't criticize Limbaugh because they know without him, these Pod People will be reduced to staring at their silent radio, mouth agape, drool running down their chins, wondering where their marching orders will come from.
In others words, Repukes can't criticize Limbaugh, because they know that without him, you wouldn't be able to find enough Repukes in Congress to rub together in a public men's room.