It can be done too -- Dr. Coburn here in OK got in the race late but he ignited the grassroots to support him and he beat the establishment candidate in the primary and the Hillary candidate in the general election. He managed to get the grassroots out in large numbers here in the State -- we worked hard and donated money. Senator Allen from NRSC was also a huge help who many of are supporting in 2008 after his awesome speech at our OK Convention.
Takes an effort to elect conservatives against an establishment candidate but a lot of people in the primary tend to be conservative that always vote and it can be done. If I was a conservative running in another State, I would be asking the Coburn folks how it was done. It was textbook how the Conservatives turned out in big numbers to support him.
I live in a very Blue state, and we have few GOPers in the pipeline. We work for the most Conservative candidates we can find - sometimes they aren't as Conservative as we would like, but any movement that way is progress.
None of our "establishment" candidates are GOPers, so every one we get is a success, even if they get trashed as being RINOs or whatever.
It can take awhile to get to the end point, but progress is significant anyway.