Just for the record, no, that's not supposed to happen. A large chunk of the party despises McCain. They hate his maverick style, his unreliability, his betrayals on issues like campaign finance, etc. George Will recently criticized McCain thusly:
In ABC's debate, McCain said: "Why shouldn't we be able to reimport drugs from Canada?" A conservative's answer is:
That amounts to importing Canada's price controls, a large step toward a system in which some medicines would be inexpensive but many others -- new pain-relieving, life-extending pharmaceuticals -- would be unavailable. [...]
There are decent, intelligent people who believe that equity or efficiency or both are often served by government setting prices. In America, such people are called Democrats.
Traditionally, Republican insiders are able to prevent a candidate like McCain from winning. That's what they did in 2000. Why is McCain succeeding now? Because the GOP is in terrible disarray. For any number of reasons, they simply could not converge on a candidate. When a party can't control its nomination process, talented (if unreliable) politicians get through. That's what happened with Schwarzenegger -- he could only get into office as a Republican in the recall election, which had no primary.
The Republicans could actually win with McCain as their nominee, but they'll have to get used to disappointment.