I think Bush and the TARP were responsible for the TEA Party wave.
Several factors happened that catapulted Rand from obscure eye surgeon to US Senator.
The TEA Party has always been strong in Kentucky if I remember correctly and Rand gave speeches to large crowds because he was interested in politics.
Then the incumbent senator (Bunning) decided not to run for a 2nd term opening up the seat.
Rand was getting a lot of requests to run. He decided to do it and he was able to raise money due to his famous dad’s network who supported Rand.
This is how he was able to raise the millions needed... Not many have this advantage or could pull it off.
Palin and endorsements came later and were very welcome but they didn’t decide the race. Rand was always going to beat Mitch’s pick as long as he could raise the money... and he did (Thank goodness!).