Thinking more about your theory....
The ‘stalking horse’ and the ‘Perot’ effect are not mutually exclusive. In its zeal to help Rudy, the GOP may unwittingly be helping McCain.
I certainly haven't seen any evidence of it. McCain is sinking like a rock in the polls and his capital is drying up. Even the MSM has turned on him. I think he is toast.
The question is will McCain's downfall create a big enough vacuum for a Fred Thompson or Newt Gingrich to fill. With both CA and NY pushing their primaries forward, I don't see how any other candidate stands a chance. Rudy can lose Iowa, NH, SC and then sweep NY and CA and have the commanding lead in electoral votes that makes him the front runner through the rest of the primaries. No conservative can raise enough money to Beat Giuliani in NY and CA.
This is the reality staring Gingrich and Thompson in the face, as well as their potential financial supporters, and will ultimately be the reason they do not run.